STANDARDIZATION 
OF  MINING  METHODS 


STANDARDIZATION 
OF  MINING  METHODS 


By  Charles  A.  Mitke 
Mining  Engineer,  Bisbee,  Arizona 


A  series  of  important  articles 
reprinted  from  Engineering  and  Mining  Journal 


FIRST  EDITION 


Published  by 
Engineering  and  Mining  Journal 

McGRAW-HILL  BOOK  COMPANY,  Inc. 

SOLE  SELLING  AGENTS 

239  WEST  39th  STREET,  NEW  YORK 
1919 


COPYRIGHT,  1919,  BY  THE 
McGRAW-HILL  BOOK  COMPANY,  INC. 


Preface 

Great  economies  in  any  business  of  production  result 
from  careful  and  thoughtful  attention  to  details,  and 
mining  is  no  exception  to  this  rule.  On  the  contrary, 
successful  mining  is  one  of  the  greatest  embodiments  of 
the  principle.  The  difference  between  the  careful  man- 
ager and  the  careless  one  is  apt  to  be  the  difference  be- 
tween profit  and  loss.  . 

Carefulness  in  management  does  not  mean  merely  the 
prevention  of  what  would  be  obvious  wastes,  such  as 
allowing  supplies  to  be  slovenly  thrown  away,  or  per- 
mitting them  to  deteriorate,  which  comes  to  the"  same 
thing;  but  also  it  means  what  may  be  vastly  more  im- 
portant, viz.,  the  prevention  of  the  unapparent  wastes, 
especially  of  labor,  by  the  continuance  of  uneconomic 
practices.  Even  in  such  an  ancient  and  simple  thing  as 
the  art  of  shovelling  there  may  be  enormous  waste  of 
man-power.  The  shoveller  may  be  provided  with  a  tool 
of  the  wrong  design  and  size.  He  may  handle  it  in  such 
a  way  as  to  consume  more  of  his  energy  than  if  he  were 
shovelling  more  ore  in  proper  posture  and  with  correct 
movements.  The  efficiency  in  shovelling  may  be  greatly 
increased  by  arranging  for  the  men  to  get  at  the  pile 
in  the  right  way.  Finally  the  work  may  be  designed 
so  as  to  reduce  the  shovelling  that  is  necessary  or  per- 
haps eliminate  it  altogether. 

This  homely  illustration  may  be  applied  to  many 
varieties  of  work  that  have  to  be  done  in  a  mine.  It 
is  the  duty  of  the  shift-bosses,  the  foremen,  the  captain, 
the  superintendent  and  finally  the  general  manager  to 
study  every  detail  with  the  view  to  effecting  the  maxi- 
mum of  economy.  There  was  never  a  time  when  this 
was  more  necessary  than  now,  when  all  industry  is 
wrestling  with  difficult  economic  problems.  Not  only 
is  it  necessary  now  to  produce  with  greater  economy 
than  ever,  but  also  working  organizations  have  been 
impaired  by  the  present  unstabilized  conditions  of  the 
labor  market,  and  much  raw  material  must  be  converted 
into  skilled  miners. 

Therefore,  I  think  that  there  can  be  no  more  im- 
portant educational  work  and  no  greater  service  to  the 

4851335 


vi  PREFACE] 

mining  industry  than  what  Mr.  Mitke  has  rendered  in 
the  preparation  of  this  series  of  articles,  which  were 
published  originally  in  the  Engineering  and  Mining 
Journal  and  are  now  republished  in  book  form  to  meet 
the  gratifying  demand  that  there  has  been  for  them. 
Mr.  Mitke,  as  mining  engineer  for  Phelps  Dodge  Cor- 
poration, had  the  opportunity  to  study  mining  practices 
in  detail  as  conducted  by  a  great  corporation  owning 
and  operating  many  mines.  It  was  his  mission  to  de- 
termine the  best  ways  of  doing  things  and  promote  their 
general  adoption  when  it  was  definitely  ascertained  what 
was  the  best.  This  resulted  in  a  considerable  degree  of 
standardization  of  mining  practices  and  that  is  what  is 
described  and  discussed  in  this  book.  It  was  proper 
that  such  a  noteworthy  contribution  for  the  advance- 
ment of  the  art  should  be  issued  in  this  convenient  and 
easily  available  form. 

W.  R.  INGALLS. 


Editorial  Comment 

Standardization  of  Mining  Methods 

(From  Engineering  and  Mining  Journal,  Nov.  9,  1918) 


ONE  of  the  great  needs  of  the  mining  industry  at 
the  present  time  is  the  working  out  and  adoption 
of  standardized  methods,  in  order  to: 

1.  Lower  the  cost   of  prospecting  and   development 
work,  which,  of  course,  ultimately  means  lowering  the 
cost  per  pound  of  metal  produced.    If  drifts,  raises,  and 
winzes  can  be  driven  for  less  money  and  at  greater 
speed  (without  a  reduction  of  wages  or  "speeding  up" 
the  men),  it  will  be  possible  not  only  to  produce  more 
metal  with  the  same  expenditure  of  money,  but  large 
bodies  of  low-grade  material,  which  cannot  be  mined 
profitably  under  present  conditions,  will  become  com- 
mercial ore. 

2.  It  is  essential  that  attention  be  paid  to  prospecting 
and  development  work,   in   order  to  maintain  present 
production,  to  say  nothing  of  the  great  need  of  increas- 
ing the  output. 

3.  As  there  is  now  a  great  shortage  of  labor,  and 
as  in  all  probability  this  will  continue  for  some  time,  it 
is  absolutely  necessary  to  standardize  operations  and 
plan  the  work  ahead  in  order  that  the  efforts  of  every 
man    may    count.      This    does    not    necessarily    mean 
"speeding  up,"  or  "more  work  per  man  per  day"   (al- 
though the  latter  is  highly  desirable),  but  it  is  impor- 
tant to  effect  a  concentration  of  labor  where  it  will  be 
productive  of  the  greatest  results. 

When  the  war  broke  out  in  1914,  prospecting  and 
development  work  was  dropped  by  practically  all  com- 
panies. Later,  when  the  price  of  metals  went  up,  labor 
troubles  set  in,  and  the  process  of  "finding  ore"  was 

vii 


viii  EDITORIAL  COMMENT 

neglected  again,  while  the  major  efforts  were  directed 
toward  maintaining  production.  Some  of  the  larger 
mines  which  had  good  ore  reserves  in  1914  have  made  a 
steady  production,  but  at  the  expense  of  their  ore  re- 
serves, which  have  been  considerably  depleted.  For  in- 
stance, to  quote  an  extreme  case,  in  one  division  of  a 
large  mine  in  southern  Arizona,  300  men  were  em- 
ployed daily  four  years  ago,  producing  10,000  to  14,000 
tons  of  ore  each  month.  This  record  has  now  dropped 
to  165  men  per  day  and  5000  to  7000  tons  monthly,  the 
decrease  being  due  largely  to  the  postponement  of  pros- 
pect and  development  work,  which  is  rapidly  shortening 
the  apparent  life  of  the  mine.  In  the  future,  therefore, 
it  is  important  that  the  cost  of  finding  ore  be  reduced  to 
a  minimum,  in  order  that  this  necessary  expenditure 
shall  yield  as  great  an  addition  to  the  ore  reserves  as 
possible. 

In  this  number  we  publish  the  first  of  a  series  of 
seven  articles  by  Charles  A.  Mitke,  dealing  with  the 
standardization  of  mining  methods,  with  a  view  to  econ- 
omy. Mr.  Mitke  is  an  engineer  of  experience,  and  has 
attacked  his  subject  with  enthusiasm.  Each  article  deals 
with  a  single  phase  of  mining  practice. 

It  is  evident  that  in  the  growth  of  the  metal-mining 
industry  each  individual  mine  will  develop  to  a  greater 
or  less  extent  a  certain  degree  of  standardization  in  its 
various  operations.  Ground-breaking,  timbering,  rais- 
ing, shaft-sinking,  and  other  features  of  mining  prac- 
tice follow  in  a  general  way  what  past  experience  has 
shown  to  be  more  or  less  effective. 

Formerly  managers  of  mines  allowed  their  foremen 
to  establish  much  of  the  detail  of  mine  operation;  and 
intelligent,  experienced  foremen  have  done  much  not 
only  for  the  individual  mine,  but  for  the  industry  as 
well.  In  some  cases  mining  practice  has  followed,  as  a 
mere  duplication,  the  procedure  instituted  by  another 
mine.  No  attempt  are  made  in  these  cases  to  establish 
a  practice  that  is  peculiarly  adapted  to  the  mine  in 
question.  The  net  result  has  been  the  growth  of  prac- 
tices that  are  more  or  less  local  in  character,  although 


EDITORIAL  COMMENT  ix 

the  migratory  miner  has  done  his  share  in  transplanting 
the  good  as  well  as  some  of  the  bad  features  of  mining 
practice  from  one  locality  to  another. 

The  past  and  present  decades  have  witnessed  a  steady 
progress  in  good  engineering.  A  first-class  manager 
now  places  upon  his  staff  the  duty  of  studying  mine 
conditions  and  the  working  out  of  methods  that  are  safe, 
economical,  and  peculiarly  adapted  to  the  mine  in  his 
charge.  Materials,  tools,  and  appliances  are  also  care- 
fully studied,  and  only  those  which  stand  the  test  of  the 
mine  conditions  and  meet  with  the  prime  requirements 
of  safety  and  economy  are  retained. 

Standardization  implies  preliminary  experimentation, 
careful  consideration  of  observations,  and  selection.  It 
does  not  imply  that  the  standard  practices  at  one  mine 
are  necessarily  the  best  for  another,  although  often 
some  features  can  well  be  adapted  by  another  mine. 
Mr.  Mitke  presents  the  results  of  his  thought  and  his 
selection  in  a  helpful  spirit,  rather  than  with  the  idea 
of  saying  the  last  word.  We  feel  that  many  of  our 
readers  will  benefit  greatly  from  his  articles.  Some  may 
differ  with  Mr.  Mitke,  and  thus  be  prompted  to  con- 
tribute suggestions  along  the  lines  he  has  taken,  as  well 
as  on  others.  The  subject  is  worthy  of  the  attention  of 
mining  engineers  at  any  time,  but  under  present  con- 
ditions it  is  extremely  important,  as  large  output,  safe 
operation,  and  economy  in  labor  and  materials  are  vital. 
We  hope  that  these  illuminating  and  suggestive  articles 
will  be  studied  not  only  by  the  operating  heads  of  mines, 
but  also  by  their  foremen  and  shift  bosses,  upon  whose 
intelligence  and  initiative  so  much  depends. 


Ventilation  of  Metal  Mines 

(From  Engineering  and  Mining  Journal,  Nov.  SO,  1918) 

AIR  is  such  an  invisible  substance  and   is  so  ap- 
parently able  to  take  care  of  itself,  that  it  is  not 
surprising  that  the  metal  miner  should  undertake  its 
regulation  last  among  the  common  demands  that  press 


x  EDITORIAL  COMMENT 

upon  his  attention.  The  air  in  a  heading  or  stope 
must  often  reach  a  condition  that  prevents  a  candle 
from  burning  before  steps  are  taken  to  better  the 
ventilation.  Even  under  these  conditions  acetylene 
lamps  have  been  used  because  they  would  operate  where 
candles  would  not.  Only  under  the  most  extreme  cir- 
cumstances would  ventilating  pipe  and  blowers  be  in- 
stalled. Too  much  reliance  has  been  placed  upon  the 
efficacy  of  ventilation  produced  by  the  exhaust  from 
air  drills.  Happily,  this  condition  is  rapidly  passing. 

Mr.  Mitke's  article  in  this  issue  is  a  good  one.  It 
reviews  the  field  in  a  way  that  will  be  appreciated  by 
mining  engineers  and  operators.  We  concur  in  hia 
opinion  that  a  quantity  standard  is  the  most  practicable. 
Under  coal-mining  conditions  a  quality  standard  is 
probably  best,  but  there  is  little  need  in  the  majority  of 
metal  mines  to  undertake  the  regular  analysis  of  the 
air  in  the  mine,  although  abnormal  conditions  may 
necessitate  this  procedure  at  times. 

The  "good  working  atmosphere"  that  Mr.  Mitke  de- 
fines— a  temperature  of  78°,  a  relative  humidity  of 
80%,  a  velocity  of  125  ft.  per  min.  and  350  cu.ft.  per 
minute  per  man — can  usually  be  readily  attained. 
Mechanical  ventilation  is  necessary  for  proper  control, 
and  this  point  has  been  thoroughly  discussed.  We  agree, 
also,  with  the  necessity  for  the  working  out  of  the 
ventilation  problem  for  the  mine  as  a  whole,  both  for 
developing  and  for  stoping.  The  insistence  upon  the 
standardization  of  small  ventilating  equipment  is  a 
good  point.  The  relative  merits  of  metal  and  canvas 
air  pipes  are  discussed. 

After  all,  improvements  in  underground  conditions 
must  find  a  measure  upon  the  cost  accounts.  The  test 
of  time  as  well  as  the  operating  results  secured  under 
a  "good  working  atmosphere"  have  been  applied  to 
Mr.  Mitke's  work  and  show  in  no  uncertain  manner  that 
attention  to  ventilation  pays.  Mine  ventilation,  held  in 
such  casual  estimation  in  many  instances,  has  an  im- 
portant significance  in  operating  economy  when  sub- 
jected to  painstaking  engineering  investigation  and 
followed  up  by  an  adequate  installation. 


EDITORIAL  COMMENT  xi 

Standard  Mining  Equipment 

(From  Engineering  and  Mining  Journal,  Dec.  21,  1918) 

SUFFICIENT  equipment,  well  cared  for  and  ac- 
O  cessible,  is  essential  in  efficient  mine  management, 
and  the  various  points  regarding  standard  equipment 
brought  out  by  Charles  A.  Mitke  in  his  article  in  this 
issue  are  examples  of  well-conducted  operations.  Not 
only  is  it  necessary  to  supply  proper  tools,  but  a  place 
to  put  them  should  also  be  provided,  so  that  each  opera- 
tion may  be  conducted  with  speed  and  dispatch.  Con- 
sidering the  old  slipshod  methods,  which,  unfortunately, 
still  prevail  in  some  districts,  it  is  not  difficult  to  under- 
stand the  comparatively  high  costs,  and  why  a  low  "tons- 
per-man"  figure  was  so  often  to  be  found.  Operators 
are  frequently  prone  to  attribute  laziness  to  their  em- 
ployees, and  though  this  may  somtimes  be  true,  not 
infrequently  a  close  study  of  underground  conditions 
will  show  that  the  men  are  not  to  blame,  and  that  the 
shortcoming  is  due  to  lack  of  system  in  the  transmission 
and  distribution  of  necessary  supplies.  The  distributive 
ideas  suggested  by  Mr.  Mitke  are  examples  of  successful 
administration,  and  cover  a  wide  variation  of  conditions. 

The  modern  machine  shop  or  warehouse  furnishes  an 
excellent  example  of  handling  tools  or  supplies.  The 
intricate  yet  simple  manner  of  "checking  out"  or 
"checking  in"  is  merely  the  outcome  of  conditions 
created  by  the  necessity  of  managing  an  establishment 
economically  and  efficiently,  and  though  this  principle 
cannot  be  brought  to  such  a  fine  point  in  underground 
mine  work,  the  results  that  may  be  achieved  by  careful 
supervision  of  supplies  are  well  worth  considering  by 
those  who  have  given  the  matter  little  attention.  It  is 
not  unusual  for  an  examination  of  old  mine  workings 
to  disclose  a  veritable  treasure  trove  in  the  shape  of 
old  shovels,  picks,  and  drill  steel,  some  of  which  are 
worthless  from  the  standpoint  of  further  usefulness; 
but  the  finding  of  such  tools  and  material  demonstrates 
the  sad  lack  of  a  "check"  system,  which,  if  enforced, 
might  have  saved  considerable  on  the  cost  sheet. 

Too  much  attention  cannot  be  paid  to  a  frequent  use 


xii  EDITORIAL  COMMENT 

of  the  Paynter  tester,  for  the  practice  of  assuming  that 
a  drill  is  doing  its  best  work  merely  because  "it  sounds 
that  way"  leads  inevitably  to  misjudgment  of  the  drill- 
ing machines.  Any  well-working  machine  must  be  kept 
in  repair,  and  it  is  not  to  be  expected  that  careless  tink- 
ering with  a  drill  is  conducive  to  good  results.  Both 
repair  work  and  testing  are  best  don©  at  a  well-ordered 
shop  where  the  right  facilities  are  provided. 

Standard  equipment  for  drifting  and  other  operations 
will,  of  course,  vary  somewhat  with  localities,  and  can 
best  be  determined  by  the  particular  conditions  encoun- 
tered, but  in  the  main  it  may  be  said  that  Mr.  Mitke's 
lists  are  typical.  In  conclusion,  the  fundamental  ideas 
are  well  emphasized  and  the  article  merits  the  attention 
of  mining  men.  Each  step  should  mesh  with  the  subse- 
quent one,  and  so  build  up  a  smooth-working,  well- 
planned  order  of  operation. 


Standardization  of  Mining  Methods 

(From  Engineering  and  Mining  Journal,      ec.  28,  1918) 

IN  THIS  issue  we  publish  the  last  one  of  a  series  of 
notable  papers  on  mining  practices.  Mr.  Mitke's 
papers  are  good.  They  cover  many  important  details 
of  mining  that  do  not  receive  the  attention  they  de- 
serve. Out  of  many  small  economies  there  appears  the 
resultant  of  a  large  economy.  Mr.  Mitke  strikes  at  two 
important  points  of  a  general  nature.  One  is  the  de- 
sirability for  the  intensive  study  of  the  smaller  features 
of  mining  practice  by  the  engineer.  Experimentation 
is  a  part  of  this  study.  The  second,  and  equally  im- 
portant point,  is  the  training  of  the  miners. 

The  success  of  modern  quantity  production  in  manu- 
facturing lies  in  the  segregation  of  processes  into 
sequential  steps  and  the  training  of  each  group  of 
workers  until  they  are  able  to  execute  their  part  thor- 
oughly and  quickly.  Necessarily,  the  cooperation  of 
the  worker  must  be  secured. 

In  mining  operations  there  are  similarities  in  prin- 


EDITORIAL  COMMENT  xiii 

ciple  to  manufacturing  methods,  although  there  is  the 
important  difference  that  the  work  is  distributed  and 
cannot  be  concentrated,  as  is  done  in  well-organized 
factories.  The  effect  of  this  is  to  throw  a  considerable 
amount  of  initiative  upon  the  miner  or  group  of  miners. 
Unrestrained  or  untrained  initiative  results  in  waste 
and  therefore  uneconomical  labor.  Efficient  supervis- 
ion and  direction  by  foremen  and  shift  bosses  go  a  long 
way  toward  remedying  this  state  of  affairs,  and  to- 
gether with  sufficient  training  of  the  workers  to  enable 
them  to  catch  the  objectives  of  the  system,  will  produce 
results  exceeding  the  expectations  of  the  most  sanguine. 


CONTENTS 


Section  I 
STANDARD  RAISES 


PAGE 


EXPANSION    OF    OPERATIONS    MAKES    STANDARDIZATION 

INCREASINGLY  IMPORTANT 1 

NEED  FOR  UNIFORMITY  IMPERATIVE 2 

CHARACTER  OF  EARLIER  TYPES  OF  RAISES 3 

DEVELOPMENT  OF  STANDARD  RAISE 3 

INFLUENCE  OF  SAFETY-FIRST  MOVEMENT 4 

STANDARD  CHUTE  DOOR 17 

STANDARD  GRATINGS  FOR  TIMBER  COMPARTMENTS 16 

Section  II 
STANDARD  MACHINE-DRILL  ROUNDS 

COST  OF  BREAKING  GROUND 19 

EARLIER  TYPES  OF  PISTON  DRILLS 20 

DEVELOPMENT  OF  STANDARD  ROUND 21 

STANDARD  ROUND  IN  TUNNEL  WORK 21 

EXPERIMENTAL  TYPES 22 

STANDARD  ROUND  FOR  DRIFTS 24 

STANDARD  ROUND  FOR  RAISES 26 

STANDARD  ROUND  FOR  TOP-SLICE  STOPES 26 

RESULTS 29 

Section  III 
VENTILATION  OF  METAL  MINES 

HUMIDITY  CAUSES  MANY  MINES  TO  SEEM  HOT 32 

CAREFUL  STUDY  OF  VENTILATION  NEEDS  NECESSARY 33 

xv 


xvi  CONTENTS 

SEPARATE  SYSTEM  FOR  DEVELOPMENT  WORK 35 

ALL  WORKINGS  MUST  BE  VENTILATED 37 

JETS  AND  BLOWERS 39 

COST  SHEETS  PROVE  VALUE  OF  GOOD  AIR 40 

VENTILATING  SYSTEMS  MAY  AID  FIRE  FIGHTING 34 

SIMPLEST  SYSTEM  USES  ONE  CENTRAL  INSTALLATION  ...  36 

VENTILATION  MAY  BE  STANDARDIZED 39 

STANDARDIZED  DOORS 45 

CLASSES  OF  STEMMING  USED 56 

Section  IV 
EXPLOSIVES 

MECHANICAL  FUSE  CUTTER 51 

CAPPING  OF  FUSES 52 

STEMMING  OR  TAMPING 53 

STEMMING  INCREASES  EFFICIENCY 55 

VALUE  OF  CLAY  FOR  STEMMING 57 

USE  OF  AMERICAN  AUGER  MACHINE 58 

LOADING  AND  BLASTING  PRACTICE 59 

GASES  FROM  EXPLOSIVES 61 

FORMULATING  OF  BLASTING  RULES  DIFFICULT 63 

Section  V 
FIRE  PROTECTION  FOR  METAL  MINES 

CAUSES  OF  MINE  FIRES 65 

EACH  MAN'S  DUTY  IN  CASE  OF  FIRE 67 

METHODS  USED  SOMEWHAT  QUESTIONABLE 68 

HELMET  WORK  69 

STANDARD  METHOD  FOR  PROTECTING  SHAFT  STATIONS 70 

PURPOSE  OF  FIRE  DOORS 71 

POSTING  OF  FIRE  RULES 75 

FIRE  FIGHTING  IN  WORKINGS 76 

EQUIPMENT 77 

GOB  FIRES 79 

MECHANICAL   VENTILATION.  .  .  78 


CONTENTS  xvii 

Section  VI 
STANDARD  EQUIPMENT 

DISTRIBUTION  OF  TOOLS  AND  SUPPLIES 82 

CARE  OF  ROCK-DRILLING  MACHINES 83 

REPAIRS  TO  ROCK  DRILLS 83 

HANDLING  STEEL  UNDERGROUND 86 

NECESSITY  FOR  STEEL  RACKS 86 

SHOVELING  90 

SHOVELS,  SHOVELING  MACHINES  AND  SCRAPERS 91 

SOUND  OF  MACHINE  No  INDICATION  OF  WORK  DONE 84 

SMALL  MACHINES 85 

STANDARD  EQUIPMENT  FOR  DRIFTING  WORK 88 

STANDARD  EQUIPMENT  IN  RAISING  AND  STOPING 89 

STANDARD  TYPE  OF  TOOL  CAR 89 

Section  VI I 
PROSPECTING  AND  DEVELOPMENT 

DANGER  FROM  MISSED  HOLES 60 

CONCRETING  MINE  SHAFT 96 

COST  OF  PROSPECT  AND  DEVELOPMENT  WORK 97 

STAGES  IN  DRILLING  AND  SHOVELING 97 

NORMAL  PROCEDURE  STANDARDIZED 100 

THE  VALUE  OF  TIME  STUDIES 101 

STANDARDIZATION  OF  OPERATIONS 102 

USE  OF  EXPLOSIVES 104 

CLEARING  THE  FACE  AND  TIMBERING 105 

IMPORTANCE  OF  CO-OPERATIVE  EFFORT 107 

LABOR  TURNOVER  PROBLEM 108 

TIME  STUDIES  RESULT  ADVANTAGEOUSLY..  ..108 


Standardization 
of  Mining  Methods 

• 

I — Standard  Raises 


THE  subject  of  standardization  is  now  receiving 
much  thought  and  consideration  and  the  details  of 
application  to  various  lines  of  industry  have 
proved  of  inestimable  value,  resulting  in  an  enormous 
increase  in  production.  The  satisfactory  results  ob- 
tained from  the  standardization  of  certain  special 
phases  of  mining  work  have  led  to  the  belief  that  the 
working  out  and  adoption  of  standard  methods  of  opera- 
tion, suitable  for  average  mining  conditions,  will  be  of 
economic  importance  in  offsetting  the  increased  costs  of 
production,  and  will  prove  equally  beneficial  both  to  the 
management  and  to  the  worker. 

EXPANSION  OF  OPERATIONS  MAKES  STANDARDIZATION 
INCREASINGLY  IMPORTANT 

The  daily  work  in  the  average  mine  consists  of  a  great 
variety  of  operations.  For  years  it  was  the  custom, 
and  in  fact  was  considered  absolutely  necessary,  for  the 
superintendent  to  give  his  personal  attention  to  all 
matters  of  daily  routine,  and  to  decide  even  the  minutest 


2  STANDARDIZATION  OF  MINING  METHODS 

details  connected  with  the  working  of  the  mine.  Under 
these  circumstances,  everything  was  conducive  to  spe- 
cialized tasks,  and  no  particular  effort  was  made  toward 
standardization  of  either  operations  or  supplies.  Such  a 
condition,  though  possible  in  small  mines,  was  not  prac- 
ticable in  larger  properties,  and  as  the  mines  developed 
and  production  increased  it  became  impossible  for  one 
man  personally  to  supervise  every  detail.  Responsi- 
bility was  necessarily  divided  among  a  number  of  de- 
partments, the  heads  of  which  were  directly  responsible 
to  the  superintendent.  This  development  led  to  individ- 
ualism, and  it  became  necessary  to  formulate  standard- 
ized rules  and  regulations  for  the  guidance  of  all  the 
different  departments. 

NEED  FOR  UNIFORMITY  IMPERATIVE 

In  the  mining  department  tools  and  supplies  required 
by  the  organization  had  hitherto  been  purchased  accord- 
ing to  the  individual  judgments  of  the  foreman,  in  con- 
sultation with  the  superintendent.  For  example,  one 
foreman  preferred  one  type  of  machine,  though  another 
showed  a  partiality  for  an  entirely  different  make.  He 
might  have  his  drifts  driven  larger,  or  his  timbers  cut 
in  different  lengths,  and  so  on.  This  necessitated  the 
carrying  in  stock  of  a  large  supply  of  repair  parts  for  the 
different  machines,  steel,  and  varied  miscellaneous  sup- 
plies and  equipment,  and  extra  cutting  of  timbers  both  on 
surface  and  underground,  all  of  which  contributed  more 
or  less  toward  inefficiency  and  higher  costs.  It  became 
evident  under  such  circumstances  that  there  was  a  great 
need  for  uniformity,  first  of  all  in  the  supplies  and  later 
in  the  operations. 

As  a  preliminary  step,  the  question  of  stope  timbers 
was  taken  up,  and  suitable  dimensions  for  the  average 
square  set  were  decided  upon  and  adopted.  The  same 
principle  was  applied  to  timbers  used  in  other  stoping 
methods,  drift  timbers,  tunnel  sets,  and  similar  equip- 
ment. Finally,  the  trend  toward  standardization  was 
developed  to  such  an  extent  that  practically  all  the 


STANDARD  RAISES  3 

timbers  used  underground  were  cut  to  standard  sizes. 
Efforts  were  made  toward  standardizing  machines  and 
supplies,  but  the  results  were  not  markedly  successful. 
One  company  which  claimed  to  have  made  advances  in 
this  direction  found  upon  investigation  that  there  were 
28  different  types  of  machines  in  constant  use  in  its 
mines  and  about  seven  kinds  of  steel. 

The  standardization  of  underground  operations  also 
presented  a  difficult  problem.  The  majority  of  miners,  as 
a  rule,  move  around  a  great  deal,  and  in  every  camp  men 
may  be  found  who  have  gained  their  experience  in  mines 
where  conditions  are  entirely  different  from  those 
under  which  they  may  happen  to  be  working.  Conse- 
quently, in  order  to  systematize  operations  it  was  found 
necessary  to  deviate  from  the  accustomed  practice  of 
"telling  a  man  what  you  want  done  and  leaving  the  rest 
to  his  own  judgment,"  and,  as  an  alternative,  to  create 
a  new  precedent  by  "telling  him  what  you  want  done, 
and  then  showing  him  the  most  approved  method  of 
doing  it."  This  rule  was  especially  applicable  in  teach- 
ing inexperienced  men  how  to  mine. 

DEVELOPMENT  OF  THE  STANDARD  RAISE 

Raises  generally  contain  several  compartments,  which 
are  used  as  manways,  timber  slides,  ore  and  waste 
chutes,  and  for  ventilation.  In  a  few  exceptional  cases 
a  raise  is  put  to  one  use  only,  in  which  event  it  has  but 
one  compartment,  and  may  or  may  not  have  any  timber, 
according  to  the  character  of  the  ground  through  which 
it  is  driven.  The  importance  of  raising  is  evident  when 
it  is  considered  that  between  400  and  500  raises  are  con- 
tinually in  process  of  being  driven  in  the  Southwest, 
at  costs  ranging  from  $3  to  $30  per  ft.  The  extraction 
of  ore  and  the  exploratory  work  necessary  to  keep  up 
or  increase  ore  reserves  require  that  approximately  this 
number  of  raises  be  kept  "running" ;  and,  as  a  rule,  when 
some  are  completed  others  are  immediately  started. 

CHARACTER  OF  EARLIER  TYPES  OF  RAISES 
In  the  past,  raises  were  driven  according  to  the  de- 


4  STANDARDIZATION  OF  MINING  METHODS 

signs  of  individual  shift  bosses  and  foremen,  and  ex- 
hibited wide  diversity  of  construction,  not  only  in  the 
different  camps  and  mines,  but  in  the  divisions  of  a 
mine  itself.  The  result  was  that  two  raises,  side  by 
side,  were  often  entirely  different  in  dimensions  and 
construction.  This  lack  of  method  proved  inefficient 
and  wasteful,  as  every  raise  was  made  a  special  case, 
and  the  men  were  unable  to  begin  work  without 
minute  directions  from  the  foremen  and  bosses.  These 
bosses,  in  turn,  would  have  two  or  three  types  in  mind, 
and  would  have  one  type  constructed  in  one  place  and 
another  type  in  the  next,  and  so  on.  In  many  of  these 
designs  the  openings  in  the  landings  were  so  small  that 
the  men  had  difficulty  in  getting  through ;  and,  as  there 
were  platforms  only  about  every  50  ft.,  and  in  some  few 
cases  none  at  all,  this  presented  a  dangerous  condition, 
and  one  likely  to  be  the  cause  of  serious  accidents. 

INFLUENCE  OF  SAFETY-FIRST  MOVEMENT 

When  the  Safety-First  movement  was  introduced  in 
the  Southwest,  about  four  years  ago,  some  of  the  first 
steps  toward  improving  conditions  were  to  cover  all 
chutes  and  manways,  put  in  more  landings,  and  pass 
laws  determining  the  distance  between  platforms  in 
all  manways,  which  reduced  the  number  of  accidents, 
but  decreased  the  workers'  efficiency  by  cutting  off  the 
ventilation  almost  entirely,  the  chute  and  manway  covers 
being  practically  air-tight.  In  some  mines,  ventilated 
by  mechanical  means  and  in  which  the  working  places 
had  become  comparatively  cool,  the  temperature  began 
to  increase,  and  the  mines  became  almost  as  hot  as 
formerly.  It  was,  therefore,  evident  that  something  had 
to  be  done  in  designing  chutes,  manways,  timber  com- 
partments and  safety  guards,  to  meet  conditions  which 
the  natural  development  of  the  mines  had  created.  This 
led  to  the  necessity  for  a  standard  raise.  It  was  es- 
sential that  such  a  raise  should  combine  the  utmost 
safety  with  the  most  efficient  working  conditions,  and 
at  the  same  time  admit  a  maximum  of  pure  air  in  order 


STANDARD  RAISES  5 

to  ventilate  the  mines  thoroughly.  Inasmuch  as  safety 
and  ventilation  make  for  efficiency,  and  efficiency 
contributes  to  economy,  it  was  the  consensus  of  opinion 
that  the  proposed  raise  must  meet  these  four  important 
requirements;  and  that  when  designed  and  adopted  as 
the  standard  the  results  would  be  beneficial  both  to  the 
men  and  the  company. 

In  the  issue  of  Jan.  18,  1918,  of  the  Journal  under  the 
caption,  "Training  a  Mining  Organization  in  Efficiency 
Methods"  (Copper  Queen  Consolidated  Mining  Co.),  an 
outline  was  given  of  the  methods  adopted  by  a  corpora- 
tion to  encourage  members  of  its  operating  force  to 
make  suggestions  and  recommendations  which  might 
prove  of  value  in  the  development  and  operation  of  its 
mines.  Recognizing  the  importance  and  necessity  for 
a  standard  raise  and  the  possibilities,  in  the  way  of 
suggestions  and  helpful  criticism,  that  might  result 
from  the  united  efforts  of  the  entire  organization,  an 
announcement  was  made  at  one  of  the  Copper  Queen 
Company's  mining  conferences  to  the  effect  that  every 
one  in  the  organization  was  to  be  given  an  opportunity 
of  working  out  a  design  for  a  standard  raise  which 
would  comply  with  the  necessary  requirements.  It  was 
arranged  that  all  suggestions  were  to  be  sent  to  me, 
and  that  I  was  to  aid  and  assist  the  men  in  having  their 
individual  designs  worked  out  intelligently,  so  that 
these  could  be  presented  either  in  the  form  of  models 
or  drawings,  accompanied  by  descriptive  papers.  The 
following  specifications  were  therefore  drawn  up: 

SAFETY 

1.  Inclined  ladders  are  preferred  to  straight  ladders,  as 
there  are  cases  on  record  where  men  who  have  become  un- 
conscious  through    being   gassed    have    fallen    on    inclined 
ladders  and  remained  there  until  taken  to  a  place  of  safety, 
whereas  on  vertical   ladders  they  would  have  fallen  and 
suffered  severe  injuries.     Inclined  ladders  are  also  easier 
to  climb. 

2.  A  landing  in  every  set.     (A  set  is  usually  about  8 
ft.  high.)     A  man  climbing  up  with  tools  and  supplies  is 
likely  to  drop  something  or  knock  a  rock  off  from  the  sides 
of  the  manway.     Should  any  one  be  following  him,  these 


6  STANDARDIZATION  OF  MINING  METHODS 

landings  would  prevent  his  being  injured  by  anything  fall- 
ing from  above. 

3.  Manways  should  be  large  enough  to  allow  the  passage 
of  a  man  wearing  an  oxygen  helmet. 

4.  Timber  compartment  should  be  of  sufficient  size  to 
permit  an  injured  man  to  be  lowered  through  it  in  a  basket. 

5.  Safety  guards,  about  3  Ms   ft.  high,  should  be  placed 
around  the  chute  and  manway  at  the  top  of  the  raise  to 
prevent  men  from  falling  in.     Grizzlies,  about  8  in.  apart, 
should  be  put  over  chutes.     These  may  be  rails  or  large 
timbers.    Small  rails  or  gratings  should  be  laid  over  timber 
compartments. 

VENTILATION 

The  area  in  the  timber  compartment  and  manway  should 
be  of  a  size  to  allow  at  least  300  cu.ft.  of  air  per  min.  to  pass 
through  for  each  man  in  the  stope.  If  there  are  a  large 
number  of  men  in  the  stope  it  will  take  a  proportionately 
large  number  of  raises  to  supply  the  amount  of  air 
required. 

EFFICIENCY 

1.  The  ladders  and  landings  should  be  so  arranged  that 
men  can  climb  up  and  down  without  inconvenience,  even 
when  carrying  powder  and  other  supplies. 

2.  The  timber  should  all  be  of  standard  size,  so  that 
when  an  order  is  sent  to  the  sawmill,  all  timber  for  the 
raise  may  be  cut  on  the  surface  and  then  sent  down  to  the 
place  where  it  is  to  be  used.     This  obviates  the  necessity 
of  any  sawing  underground. 

3.  The  raise  set,  with  few  exceptions,  should  be  the  same 
height  as  the  stope  set,  that  the  timbering  of  the  raise  may 
match  the  timbers  of  the  stope,  and  allow  workings  from 
the  raise  set  to  be  continued  into  the  stope. 

4.  The  bottom  of  the  chutes  should  rest  on  solid  ground, 
not  on  wooden  flooring.    The  solid  ground  will  not  give  way 
when  ore  is  dumped  on  it  from  above,  and  it  requires  only 
a  chute  mouth,  whereas  a  wooden  chute  bottom  would  need 
a  great  deal  of  repairing. 

6.  The  timber  compartment  should  be  large  enough  to 
allow  of  timbers  being  hoisted  into  the  stope. 

ECONOMY 

As  the  cost  of  raising  in  general  is  high,  varying  from 
$3  to  $30  per  ft.,  it  is  important  that  expenditures  for  labor, 
timber,  and  other  requisites  be  reduced  to  a  minimum. 

The  working  force  evinced  much  interest  and  en- 
thusiasm over  the  specifications  outlined,  and  there  was 
no  little  friendly  rivalry  between  the  bosses  of  the 
different  divisions.  At  consecutive  meetings  of  the 
Copper  Queen  mining  conference,  the  shift  bosses  pre- 
sented outlines  of  their  individual  plans,  which  were 


STANDARD  RAISES  7 

discussed,  the  relative  merits  and  defects  being  brought 
out,  and  several  ideas  set  aside  for  further  considera- 
tion. A  brief  description  of  some  of  the  more  important 
designs  submitted  follows: 

Fig.  1  represents  the  first  attempt  at  a  new  type  of 
raise,  showing  manway  and  timber  compartment.  The 
manway  has  incline  ladders,  arranged  as  shown  in  both 
the  plan  view  and  vertical  section.  This  plan  was 
worked  out  by  one  of  the  bosses  and  is  designed  for  a 
six-post  raise.  The  area  of  the  chute  is  equal  to  that 
of  the  manway  and  timber  compartment  combined,  but 
the  drawing  of  the  chute  is  omitted.  The  air  space, 
for  ventilating  purposes,  in  the  timber  compartment  is 
5.2  sq.ft.,  and  in  the  manway  3.4  sq.ft.,  making  a  total 
of  8.6  sq.ft.  Criticism  on  this  raise  was  that  it  was 
somewhat  complicated,  as  the  boards  in  the  landings  re- 
quired extra  cutting  for  each  floor.  It  contained  an 
angular  timber  compartment,  and  the  manway  was 
situated  near  the  chute,  which  meant  that  it  would  al- 
ways be  dirty  from  fine  ore  working  out  of  the  chute. 
This  raise  failed  from  the  standpoints  of  efficiency, 
economy,  and  ventilation. 

Another  attempt  at  a  standard  six-post  raise  is 
shown  in  Fig.  2,  with  a  much  smaller  timber  compart- 
ment. It  is  also  difficult  to  make,  as  miners  seldom  or 
never  have  a  full  set  of  carpenter's  tools.  Another  ob- 
jection is  that  the  timber  compartment  has  an  area  of 
only  2.8  sq.ft.,  and  the  manway,  only  3.5  sq.ft.,  making 
a  total  area  of  but  6.3  sq.ft.  Criticism  of  this  raise 
showed  that  the  design  was  inefficient,  uneconomical,  and 
imperfect  as  regards  ventilation. 

In  Fig.  3  the  manway  and  timber  compartment  con- 
tains the  largest  area  for  ventilating  purposes  among 
the  designs  thus  far  considered,  the  total  number  of 
square  feet  of  air  space  being  10.1.  It  is  designed  for 
a  six-post  raise,  is  easily  built,  and  there  are  few  ob- 
jections from  an  operating  standpoint.  It  has  a  large 
timber  compartment,  permitting  an  injured  man  to  be 
lowered  through  it  in  a  basket.  There  is  also  room 


STANDARDIZATION  OF  MINING  METHODS 


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STANDARD  RAISES  9 

for  a  helmet  man  to  go  up  and  down  the  manway  after 
two  1  x  12-in.  boards  are  loosened. 

Fig.  4  shows  a  rather  complicated  manway  for  a 
six-post  raise  and  presents  many  difficulties  from  an 
operating  standpoint.  The  air  space  in  the  timber 
compartment  is  4.5  sq.ft.,  and  in  the  manway  3.6  sq.ft., 
making  a  total  of  8.1  sq.ft.  The  helmet  men  can  go  up 
and  down  the  ladders,  but  the  building  of  this  manway 
would  be  difficult  and  expensive.  It  failed  in  economy 
and  efficiency. 

In  Fig.  5  the  manway  and  timber  compartment  is 
similar  to  that  shown  in  Fig.  3,  but  is  designed  for  a 
crib  raise,  whereas  Fig.  3  is  intended  for  a  six-post 
raise.  The  timber  compartment  contains  5.7  sq.ft.  and 
the  manway  5.3  sq.ft.,  making  a  total  of  11  sq.ft.  It 
is  therefore  especially  advantageous  from  the  stand- 
point of  ventilation,  and  there  is  considerable  room  at 
the  different  landings  to  go  from  one  ladder  to  another, 
so  that  it  also  fulfills  some  of  the  efficiency  requirements. 
Also,  most  miners  are  familiar  with  this  type  of  man- 
way, which  is  a  decided  advantage.  One  criticism  was 
that  the  ladders  were  12  ft.  long,  which  was  an  ob- 
jection from  the  point  of  view  of  safety. 

Fig.  6  shows  another  type  of  manway  for  a  crib 
raise,  with  a  good-sized  compartment  for  hoisting  tim- 
ber— large  enough  for  a  man  to  be  lowered  through  in 
a  basket.  In  case  of  necessity  a  helmet  man  with  ap- 
paratus can  climb  up  and  down  the  ladderway.  The 
timber  compartment  contains  5.1  sq.ft.,  the  manway 
3.3  sq.ft.,  making  a  total  of  8.4  sq.ft.  The  ladders  are 
inclined.  This  raise  fulfills  the  requirements  regarding 
efficiency,  as  it  contains  a  good  traveling  manway. 

The  manway  illustrated  in  Fig.  7  shows  all  ladders 
arranged  vertically,  although  they  are  only  one  set 
high.  As  regards  ventilation,  there  is  a  total  area  of 
9.6  sq.ft.  A  novel  idea  is  shown  in  the  chutes,  as  break- 
ers are  placed  in  each  set  on  opposite  sides  of  the  chute 
(as  indicated  in  drawing  on  the  left  in  Fig.  7).  Any 
ore  which  starts  from  the  top  will  not  drop  down  ver- 


10 


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tically  and  form  a  solid  mass  in  the  bottom  of  the  chute, 
but  will  strike  these  breakers,  zigzagging  from  one  to 
the  other  until  it  reaches  the  bottom.  A  chute  of  this 
sort  seldom  needs  punching,  as  it  rarely  "hangs  up." 
The  manway  is  easily  made,  but  did  not  prove  popular 
with  the  men,  although  it  is  used  in  several  other  camps. 

The  square  set  raise  shown  in  Fig.  8  contains  a  total 
air  space  of  13  sq.ft.  It  has  two  timber  compartments, 
and  may  have  either  vertical  or  inclined  ladders.  The 
illustration  is  interesting  in  that  it  represents  a  smaller 
chute  but  larger  air  space.  The  chief  objections  raised 
were  high  cost  of  construction  and  cost  of  upkeep,  as 
the  chute  would  have  a  tendency  to  break,  not  only  on 
the  manway  side  but  on  the  opposite  side,  where  it 
would  be  difficult  to  make  repairs. 

Figs.  9,  10,  11  and  12  are  types  of  small  special  raises, 
containing  manways,  timber  compartments,  and  chutes, 
designed  for  use  in  top  slices,  small  square  set  stopes, 
and  similar  workings.  The  advantage  of  small  raises 
of  this  kind  is  that  they  require  openings  driven  through 
the  ground  only  about  half  the  size  of  the  standard 
raise,  but  they  also  possess  a  decided  disadvantage  in 
the  limited  capacity  of  their  chutes. 

After  considering  the  various  designs,  Figs.  3,  5,  6, 
9,  10,  11  and  12  were  selected  as  representing  ideas 
having  considerable  merit.  Slight  alterations  and  im- 
provements, however,  were  made  to  the  original  plans 
of  Figs.  3  and  5,  as  may  be  seen  by  referring  to  Figs. 
13  and  14.  In  Fig.  13  it  will  be  noticed  that  the  changes 
in  the  manway  are  such  as  to  allow  greater  space  for 
traveling,  and  stronger  construction,  heavier  timbers 
being  used  in  the  manway  and  timber  compartments 
than  were  required  in  the  original  design  (Fig.  3). 
Fig.  13  also  shows  a  greater  area  for  ventilation.  The 
chief  points  of  difference  between  Figs.  5  and  14  lie  in 
the  fact  that  in  Fig.  14  the  ladders  have  been  shortened 
so  as  to  make  it  safer  for  a  man  going  from  one  ladder 
to  another.  According  to  the  design  in  Fig.  14,  he 
can  fall  only  8  ft.;  whereas  in  Fig.  5  it  would  be  pos- 


14  STANDARDIZATION  OF  MINING  METHODS 

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STANDARD  RAISES  15 

sible  for  him  to  drop  12  ft.  Smaller  timbers  are  used 
between  the  manway  and  timber  compartment,  which 
improves  the  ventilation. 

Of  the  designs  illustrated  in  Figs.  6,  9,  10,  11,  12,  13 
and  14,  Figs.  9,  10,  11  and  12  are  intended  for  use 
in  the  special  cases  mentioned  above,  and  Figs.  13  and 
14  are  designed  to  meet  conditions  when  it  becomes 
necessary  to  construct  a  manway  in  a  limited  space. 
Fig.  6  was  found  to  have  many  possibilities,  and,  after 
a  few  minor  changes  were  made,  the  improved  design, 
Fig.  15,  came  nearer  complying  with  the  requisites  for 
a  standard  raise  than  any  of  the  other  plans  submitted. 
It  was  therefore  adopted  as  the  standard  for  the  com- 
pany's mines. 

In  comparing  Fig.  6  with  Fig.  15  it  will  be  seen  that 
the  changes  were  slight.  Fig.  15  has  a  larger  timber 
compartment  than  Fig.  6,  and  also  larger  sized  openings 
in  the  different  landings  of  the  manway.  Fig.  15A 
is  identical  with  Fig.  15,  with  the  exception  that  the 
latter  gives  the  dimensions  of  a  manway  and  timber 
compartment  for  a  crib  raise,  whereas  Fig.  15A  is  the 
same  design  for  a  six-post  square  set  raise,  using 
10  x  10-in.  timbers.  Experience  has  shown  that  there 
are  few  accidents  in  a  manway  of  this  kind,  as  it  con- 
tains all  the  safety  requirements,  is  satisfactory  as 
regards  ventilation  and  efficiency,  and  also  possesses 
the  following  advantages: 

1.  The  ladders  are  inclined. 

2.  It  is  impossible  for  a  man  to  fall  more  than  one 
set,  which  is  about  eight  feet. 

3.  A  man  going  up  the  ladder  with  supplies  would 
not  injure  any  one  below,  should  he  drop  anything. 

4.  The  timber  compartment  is  large,  allowing  an 
injured  man  to  be  taken  through  in  a  basket. 

5.  A  man  wearing  an  oxygen  helmet  can  get  through 
all  the  openings. 

6.  On  top  of  the  raise  there  are  guard  rails  3i  ft. 
high  around  the  chute  and  manway.    A  grating,  illus- 
trated in  Figs.  16  and  17,  is  put  over  the  timber  com- 


16  STANDARDIZATION  OF  MINING  METHODS 

partment,  and  grizzlies  of  either  timber  or  rail  are  laid 
over  the  chutes. 

7.  From  the  point  of  view  of  ventilation,  the  area 
is  sufficient  to  allow  942  cu.ft.  of  air  per  min.  to  pass 
through  when  the  air  is  moving  at  a  velocity  of  100  ft. 
per  min.,  which  is  sufficient  for  three  or  four  men  in  a 
stope  of  ordinary  size.    If  the  stope  is  larger  and  has 
more  men  working  in  it,  additional  raises  should  be 
put  up  to  increase  the  quantity  of  air  in  proportion  to 
the  number  of  men.     The  extra  raises  will  also  give 
additional  chute  capacity  to  take  care  of  the  increased 
tonnage. 

8.  All  timbers  are  of  standard  size;  therefore  no 
cutting  underground  is  required. 

9.  The  openings  through  the  landings  are  large  and 
roomy,  so  that  a  man  may  easily  pass  through  them. 

10.  Timber  can  readily  be  hoisted  through  the  tim- 
ber compartment  into  stopes. 

11.  The  solid  ground  is  left  at  the  bottom  of  the 
chute,  so  that  the  ore,  which  drops  100  ft.,  will  strike 
on  the  solid  and  not  wear  out  any  chute  bottoms,  which 
must  be  replaced  from  time  to  time.     Only  a  chute 
mouth  is  put  in,  which  requires  little  repair  work. 

12.  The  construction  of  such  a  raise  is  economical 
on  account  of  its  simplicity,  standard  length  of  timbers 
and  the  fact  that  most  miners  are  more  or  less  familiar 
with  it.    It  has  proved  a  success  at  the  Copper  Queen 
Company's  mines,  and  has  also  achieved  considerable 
popularity  in  other  camps  in  the  Southwest  where  it  has 
received  a  fair  trial. 

STANDARD  GRATINGS  FOR  TIMBER  COMPARTMENTS 

Fig.  16  illustrates  the  style  of  grating  to  be  placed 
over  timber  compartments  of  the  Figs.  13  and  14  type, 
and  Fig.  17  represents  the  grating  for  Figs.  15  and 
15A.  These  gratings  should  both  be  of  standard  size 
(as  indicated  in  the  drawings)  and  made  in  the  com- 
pany's shops  on  the  surface.  When  they  are  taken 
underground,  the  only  thing  necessary  is  to  fasten  the 


STANDARD  RAISES 


17 


'  iron  Bar  l< 


FIG. 16 


<:'t"Bo/+  through  /ftpe 
fai/s  3' 


tvurr  TO  DQ  jt         *•••• 

from  End  of /fa/'/ 


i-J. 


PIO.J7 


FIG, 


hinges  to  the  timbers  on  the  sides  of  the  raise. 

STANDARD  CHUTE  DOOR 

A  circular  chute  door  is  shown  in  Fig.  18  which  is 
to  be  used  in  the  chute  of  the  standard  raise  (Figs. 


18  STANDARDIZATION  OF  MINING  METHODS 

15  and  15A).  This  door  is  convenient  and  is  easily 
operated  with  a  piece  of  gas  pipe,  which  is  used  as  a 
lever.  Though  the  raises,  gratings,  and  door  described 
are  given  as  the  standards  in  their  particular  line,  this 
does  not  in  any  sense  imply  that  they  may  not  be  changed 
should  a  better  way  be  worked  out.  They  merely  repre- 
sent the  best-known  and  most  efficient  method  at  the 
mines  in  which  they  have  been  installed. 

The  word  "standard"  is  likely  to  be  misleading  in 
that  it  has  two  meanings,  its  most  commonly  accepted 
definition  indicating  something  which  has  attained  a 
state  of  perfection  and  is  therefore  not  subject  to 
change.  However,  in  its  application  to  working  methods 
it  has  a  much  broader  interpretation,  and  it  has  been 
defined  thus: 

"A  standard  is  simply  a  carefully  thought  out  method 
of  performing  a  function,  or  carefully  drawn  specifica- 
tions covering  an  implement  or  some  article  of  stores 
or  of  product.  The  idea  of  perfection  is  not  involved 
in  standardization.  The  standard  method  of  doing  any- 
thing is  simply  the  best  method  that  can  be  devised 
at  the  time  the  standard  is  drawn.  .  .  .  Improve- 
ments in  standards  are  wanted  and  adopted  whenever 
and  wherever  they  are  found.  There  is  absolutely 
nothing  in  standardization  to  preclude  innovation.  But 
to  protect  standards  from  changes  which  are  not  in 
the  direction  of  improvements,  certain  safeguards  are 
erected.  These  safeguards  protect  standards  from 
change  for  the  sake  of  change.  All  that  is  demanded 
...  is  that  a  proposed  change  in  a  standard  must 
be  scrutinized  as  carefully  as  the  standard  was  scruti- 
nized prior  to  its  adoption.  Standards  adopted  and  pro- 
tected in  this  way  produce  the  best  that  is  known  at 
any  one  time.  Standardization  practiced  in  this  way 
is  a  constant  invitation  to  experimentation  and  improve- 
ment."— Morris  L.  Cooke,  Bulletin  No.  5,  Carnegie 
Foundation  Series. 


Section  II 

Standard 
Machine-Drill   Rounds 


THOUGH  different  operations  connected  with  the 
driving  of  drifts  and  raises  are  important,  in  that 
they  have  a  bearing  on  the  cost,  they  are,  never- 
theless, subordinate  to  the  actual  drilling.     Success  in 
drilling  depends  largely  on  the  type  of  machine-drill 
round  which  is  used,   and  involves  a  number  of  im- 
portant questions,  such  as  the  "depth  of  round  to  be 
pulled"  (advance),  "placing  of  the  cut,"  and  "direction 
and  numbers  of  holes  necessary." 

Too  LITTLE  CONSIDERATION  GIVEN  TO  COST  OF 

BREAKING  GROUND 

The  character  of  machine  rounds  is  of  the  greatest 
importance  as  well  as  being  a  determining  factor  in  the 
cost  of  breaking  ground  when  drifting  and  raising,  but 
it  is,  in  a  great  measure,  left  to  the  individual  judgment 
of  the  miner,  who  follows  the  old-time  method  employed 
in  hand  drilling  and  places  his  round  according  to  the 
slips,  fractures,  or  crevices  which  appear  in  the  face 
of  the  rock.  This  he  believes  to  be  of  the  utmost  im- 
portance, the  only  other  worthy  consideration  being 
the  number  of  holes  to  be  drilled.  If  the  ground  does 
not  break  satisfactorily,  more  holes  are  considered  neces- 
sary, and  the  prevailing  idea,  not  only  among  the  miners 


20  STANDARDIZATION  OF  MINING  METHODS 

but  among  many  shift  bosses  and  foremen,  is  that  the 
principal  factor  governing  the  breaking  of  ground  is 
the  number  of  holes  drilled,  without  special  regard  to 
the  direction  in  which  they  are  driven,  except  that  their 
position  is  determined  by  the  faults  and  slips  occurring 
in  the  face.  In  fact,  it  is  common  practice,  in  cases 
where  a  drill  round  does  not  break,  for  the  foremen  and 
bosses  to  order  the  miner  to  "put  in  more  holes,"  without 
making  mention  of  the  direction  or  depth  they  should 
be  driven. 

An  estimate  of  the  average  advance  per  round  in 
ordinary  ground  would  be  from  3i  to  4i  ft.,  with  5  ft. 
considered  good  work.  At  present,  practically  all  rounds 
are  drilled  from  6  to  18  in.  deeper  than  the  actual  ad- 
vance made.  Many  miners  drill  5  ft.  per  round,  but  the 
total  footage  made  at  the  end  of  the  month  will  average 
only  3  ft.  per  round.  This  is  due  almost  entirely  to  the 
character  of  the  round. 

In  rounds  where  the  advance  is  far  less  than  the 
ground  drilled,  the  fault  in  nearly  every  case  lies  in 
the  position  of  the  cut  holes,  as  the  round  will  usually 
break  no  deeper  than  the  depth  of  the  cut  holes,  regard- 
less of  what  depth  the  other  holes  are  drilled.  Conse- 
quently, on  the  position  and  depth  of  the  cut  holes 
depends  the  distance  of  advance  of  the  round. 

EARLIER  TYPES  OF  PISTON  DRILLS  RESPONSIBLE  FOR 
LOWER  POSITION  OF  CUT  HOLES 

The  old  type  of  piston  drill,  with  which  many  miners 
gained  their  first  experience  in  machine  drilling,  is  re- 
sponsible for  the  placing  of  the  cut  holes  in  the  bottom 
of  the  drift,  as  it  was  necessary  to  point  the  holes 
downward,  although  this  is  a  difficult  position  from 
which  to  break  the  ground  when  the  round  is  blasted. 
Experience  has  proved  to  the  miners  that  it  is  possible 
to  break  the  ground  with  this  type  of  round ;  therefore 
it  is  hard  for  them  to  believe  that  a  round  having  the 
cut  holes  placed  in  some  other  position  may  give  not 
only  equally  good  results,  but  even  better,  and  do  more 
toward  removing  all  the  ground  drilled  than  was  pos- 


STANDARD  MACHINE  DRILL  ROUNDS  21 

sible  with  the  old  type  of  round.  No  round  is  advanced 
more  than  the  depth  of  the  holes  drilled,  but  the  purpose 
in  working  out  a  standard  round  is  to  determine  upon 
the  type  which,  under  average  conditions,  will  break 
all  of  the  ground  drilled,  in  both  short  and  deep  rounds. 
By  accomplishing  this,  the  average  footage  per  man  per 
shift  would  be  considerably  increased,  and  this  would 
necessarily  result  in  a  decrease  in  cost. 

STANDARD  ROUND  CUSTOMARY  IN  TUNNEL  WORK 

The  realization  of  the  advantage  of  evolving  a  stand- 
ard round,  though  comparatively  novel  in  mining,  is  not 
new  in  tunnel  work,  in  the  performance  of  which  rounds 
are  usually  driven  on  contract,  and  it  is  to  the  interest 
of  the  contractor  to  develop  a  round  that  will  remove 
the  most  ground  with  the  least  drilling  and  a  minimum 
amount  of  powder.  Remarkable  results  have  been  ob- 
tained in  tunnel  driving,  as,  for  example,  in  the  work  at 
the  Mount  Royal  tunnel,  in  which  a  record  of  810-ft.  per 
month  was  established;  in  operations  by  the  Arizona 
Copper  Co.,  showing  799  ft.  per  month,  and  by  the 
Laramie-Poudre,  653  ft.  per  month;  and  at  the  present 
time  a  tunnel  is  being  driven  in  the  Southwest  that 
averages  20  ft.  per  day,  or  10  ft.  per  shift.  Though 
the  advance  secured  by  the  use  of  deep  rounds  in  tunnel 
work  cannot  be  attained  in  small  mining  drifts,  never- 
theless a  type  of  round  may  be  used  which  will  show  a 
material  average  increase  in  the  footage  over  records 
made  with  the  old  type  of  rounds. 

DEVELOPMENT  OF  THE  STANDARD  ROUND 

Some  time  ago,  in  an  effort  to  secure  a  type  of  round 
which  would  break  practically  all  of  the  ground  drilled 
and  which  might  be  considered  as  a  standard  for  aver- 
age conditions,  a  number  of  experiments  were  made  at 
the  Copper  Queen  mine.  These  were  carried  on  in  all 
kinds  of  ground  and  under  varying  conditions,  so  as  to 
establish  a  basis  for  a  round  which  could  be  adopted  as 
standard. 

One  of  the  difficulties  encountered  in  conducting  these 
experiments  was  the  opposition  of  the  older  men  who 


22  STANDARDIZATION  OF  MINING  METHODS 

had  been  mining  from  15  to  25  years.  "I  have  been 
mining  for  20  years,  and  none  of  these  young  fellows 
'round  here  can  tell  me  how  to  put  in  a  round" ;  "These 
blueprint  rounds  can  only  be  drilled  in  the  office  on 
paper,  but  not  in  the  mine  underground,"  and  similar 
expressions  reflect  the  opposition  that  the  proposition 
encountered.  However,  when  it  was  properly  explained 
to  the  men  that  the  company  would  assume  all  responsi- 
bility in  regard  to  breaking  the  ground,  and  that  if  the 
round  failed  there  would  be  no  discredit  to  the  miner, 
they  did  their  best  with  the  particular  round  in  question 
and  afterward  frequently  presented  other  types  of 
rounds  with  which  they  desired  to  experiment.  Another 
obstacle  which  had  to  be  overcome  was  the  objection  of 
the  men  to  the  use  of  one  type  of  round  in  all  classes 
of  ground,  regardless  of  fractures,  water  courses,  faults 
and  other  irregularities  encountered.  In  their  opinion 
these  variable  conditions  required  special  types  of 
rounds,  the  position  and  number  of  holes  varying  ac- 
cording to  the  situation  of  the  fractures  and  faults  in 
the  face,  all  of  which  should  be  taken  into  account. 

EXPERIMENTAL  TYPES  USED  IN  DEVELOPMENT  OP 
STANDARD  ROUND 

Some  of  the  experimental  types  of  rounds  which  have 
been  tried  out  should  prove  of  interest.  Fig.  1  repre- 
sents the  old  type  of  12-hole  round,  with  the  cut  holes 
placed  at  the  lower  part  of  the  drift  face.  The  machine 
column  and  arm,  upon  which  a  No.  18  Leyner  was 
mounted,  is  diagrammed  at  the  right.  The  height  of 
the  arm  above  the  bottom  of  the  drift  was  7i  ft.  when 
the  back  hole  was  drilled.  It  was  lowered  1  ft.  for 
the  three  breast  holes,  then  lowered  to  6  ft.  in  height 
for  the  next  six  holes,  and  finally  the  machine  was  low- 
ered as  far  as  possible  for  the  two  lifters.  This  round 
was  drilled  in  average  ground.  Fig.  1A  is  a  side  view 
of  the  same  round,  and  shows  where  the  holes  bottomed 
when  the  round  was  drilled  6  ft.  in  depth.  However, 
when  the  shots  were  fired,  the  actual  advance  at  the 
drift  was  only  4  feet. 


STANDARD  MACHINE  DRILL  ROUNDS 


23 


Another  drift  was  begun  in  somewhat  harder  ground, 
and  the  round  shown  in  Fig.  2  was  tried  out.  The 
lay-out  is  almost  identical  with  that  shown  in  Fig.  1, 
although  the  miner  who  did  the  drilling  claimed  he 


was  using  an  absolutely  new  design  of  round.  The 
results  obtained  were  similar  to  those  secured  in  the 
round  shown  in  Fig.  1. 

Fig.  3  shows  a  round  used  in  softer  ground,  and  con- 
sequently a  fewer  number  of  holes  was  required.     The 


24  STANDARDIZATION  OF  MINING  METHODS 

round  was  drilled  to  a  depth  of  5  ft.  The  actual  advance 
was  only  4i  feet. 

A  13-hole  round  drilled  in  hard  ground,  with  the 
depth  to  which  each  hole  was  drilled,  is  shown  in  Fig.  4. 
In  blasting,  a  50-lb.  box  of  40%  gelatin  was  used,  and 
3i  ft.  of  ground  was  broken,  leaving  the  face  well 
squared  up. 

The  nine-hole  round  shown  in  Fig.  5  was  drilled  in 
uniformly  soft  porphyry.  In  one  drift  4.4  ft.  of  advance 
was  made  during  each  of  10  consecutive  days,  5i  ft. 
being  the  average  depth  of  each  round.  Sixty  sticks 
of  30%  gelatin  per  round  were  used  in  this  instance. 

Fig.  6  shows  the  plan  followed  in  a  13-hole  round 
that  was  used  in  a  number  of  drifts  driven  in  good 
average  ground,  the  arrows  in  the  face  showing  where 
the  holes  bottomed.  One  drift  showed  an  advance  of 
5i  ft.  for  13  consecutive  days.  This  type  of  round 
represented  something  new  for  the  miners,  and  they 
first  ridiculed  it  by  calling  it  a  "blueprint  round." 
However,  when  the  men  discovered  the  footage  which 
they  could  make  by  this  arrangement  of  holes,  they 
did  not  hesitate  to  use  it  in  their  work. 

Fig.  7  shows  a  14-hole  round,  which  was  used  in  hard 
ground.  The  rounds  described  in  Figs.  2  and  4  were 
tried  in  this  exceptional  ground,  but  as  a  rule  the  ad- 
vance was  equivalent  to  half  what  it  should  have  been 
for  the  ground  drilled.  In  the  rounds  shown  in  Fig.  7 
the  advance  was  nearly  always  equal  to  the  total  ground 
drilled. 

Fig.  8  shows  a  13-hole  round  used  in  a  number  of 
drifts  in  average  ground.  In  one  drift  8-ft.  steel  was 
used,  and  the  drift  was  advanced  7$  ft.  for  a  period  of 
15  consecutive  days.  The  cut  holes  usually  met  in  the 
center.  On  one  occasion  after  the  holes  were  drilled  the 
angles  were  measured  and  plotted,  as  shown  in  the 
drawing.  When  this  round  was  fired  it  was  advanced 
71  feet. 

STANDARD  MACHINE-DRILL  ROUND  FOR  DRIFTS 
Figs.  9  and  9A  show  the  types  of  rounds  which  were 


STANDARD  MACHINE  DRILL  ROUNDS 


25 


finally  adopted  as  standard,  and  both  represent  slight 
modifications  of  Fig.  8,  with  which  the  best  results 
were  obtained.  The  cut  holes  are  situated  in  the  center, 
and  the  burden  is  properly  distributed  on  the  different 


holes.  The  drift  is  arched  so  that  it  may  be  used  for 
motor  haulage,  or,  if  it  is  to  be  timbered,  three  back 
holes  are  used.  The  numbers  at  the  collars  of  the  holes 
represent  the  order  in  which  the  shots  are  to  be  fired, 
and  the  two  center  holes,  numbered  "1,"  are  drilled  to 
meet  and  fired  simultaneously.  This  round  was  drilled 
through  ground  which  contained  many  slips,  water- 
courses and  fractures,  and  compared  favorably  with  an- 
other drift  in  similar  ground  where  the  miner  used  a 
variable  type  of  round  to  suit  the  constant  changes  in 


26  STANDARDIZATION  OF  MINING  METHODS 

the  ground.  This  latter  round  advanced  only  about  two- 
thirds  of  the  footage  made  by  the  standard  round. 

Fig.  9  is  a  13-hole  round  for  average  ground,  and 
Fig.  9A  is  a  16-hole  round  for  hard  ground,  though  in 
softer  ground  from  5  to  13  holes  are  frequently  found  to 
be  sufficient.  In  these  cases  the  center  cut  is  put  in  and 
the  same  principle  carried  out  as  in  the  harder  ground, 
but  the  number  of  holes  around  the  sides  and  bottom 
of  the  drift  is  reduced. 

DEVELOPMENT  OF  A  STANDARD  ROUND  FOR  RAISES 

The  method  of  procedure  followed  in  the  development 
of  a  standard  round  for  drifts  was  also  adopted  in  work- 
ing out  a  standard  round  for  raises,  and  from  the  many 
designs  presented  and  tried  out  those  shown  in  Figs.  10 
and  11  were  selected  as  the  most  efficient.  Fig.  10  is  an 
example  of  the  end  cut  in  a  4  x  6-ft.  raise  and  was  a 
popular  cut  with  the  miners,  although  Figs.  11  and  11 A 
represent  the  standard  type  of  round  adopted  for  raises. 
Fig.  11  is  used  in  a  small  raise  4x6  ft.,  whereas  Fig. 
11 A  is  intended  for  a  4  x  8  ft.  raise.  In  both  cases  the 
center  cut  is  used.  In  the  comparative  tests  between 
results  of  the  methods  shown  in  Figs.  10  and  11,  it  was 
found  that  Figs.  11  and  11 A  showed  a  better  footage 
per  man  shift  than  could  be  obtained  with  Fig.  10. 

STANDARD  ROUND  FOR  TOP-SLICE  STOPES 

It  is  impracticable  to  devise  a  standard  round  that 
will  be  suitable  for  all  methods  of  stoping.  For  ex- 
ample, in  cut-and-fill  one  or  two  holes  properly  situated 
may  break  as  much  ore  as  a  round  of  holes  in  a  square- 
set  stope.  However,  in  horizontal  top-slicing  there  is 
considerable  uniformity  in  opening  up  lead  sets,  so  in 
this  special  case  the  same  principle  which  is  practised 
in  the  standard  round  in  drifts  has  been  applied  to  this 
method  of  stoping,  with  satisfactory  results,  and  is 
shown  in  Fig.  12. 

When  standard  rounds  were  adopted,  orders  were 
given  to  the  foremen  to  have  blueprints  made  and  posted 
in  all  the  mine  offices,  so  that  the  bosses  might  become 
familiar  with  them,  and  instructions  were  issued  to 


STANDARD  MACHINE  DRILL  ROUNDS 


27 


use  the  standard  rounds  in  all  prospect  and  development 
work.  Wooden  models  with  wires  showing  the  drill 
holes  were  then  made  and  placed  in  the  mine  offices 


28  STANDARDIZATION  OF  MINING  METHODS 

and  later  transferred  to  the  miners'  change  room,  so 
as  to  give  the  men  an  opportunity  to  familiarize  them- 
selves with  the  standard  round.  Drill  instructors  were 
appointed  from  among  the  miners  who  had  made  the 
best  footage  with  the  standard  rounds,  and  they  were 
sent  to  train  all  the  machine  men. 

It  is  advisable  that  the  drill  instructor  should  be  a 
man  who  has  had  experience  in  drilling  different  types 
of  machine  rounds  in  other  camps  for  different  classes 
of  ground.  Unless  he  has  had  a  wide  experience  of  this 
nature,  the  men  whom  he  is  supposed  to  instruct,  and 
who  have  been  in  other  camps  themselves,  are  in  a  posi- 
tion to  argue  with  him  and  tell  him  of  the  success  of 
certain  other  rounds  in  these  camps.  If  he  is  not  in  a 
position  to  prove  to  them  that  such  a  round  is  not  effi- 
cient in  the  class  of  ground  in  which  they  are  at  present 
working,  his  efforts  as  an  instructor  will  be  unsuccess- 
ful. It  is  therefore  necessary  for  him  to  have  drilled 
other  types  of  rounds  beside  the  standard,  so  that  he 
may  be  able  to  draw  comparisons  and  prove  its  worth  to 
the  individual  miners. 

The  instructor  starts  with  one  miner  at  a  time,  in- 
structing him  how  to  drill  the  new  type  of  round,  and 
stays  with  him  until  the  miner  becomes  proficient  and 
is  convinced  that  he  can  secure  further  advance  with 
the  standard  than  he  could  with  the  other  types.  After 
one  miner  has  mastered  the  standard,  the  instructor 
spends  several  days  with  another,  and  so  on  until  all 
the  machine  men  have  become  accustomed  to  the  new 
methods. 

In  some  cases  the  duty  of  instructing  the  men  may  be 
performed  by  a  development  boss,  who  acts  both  as  in- 
structor and  supervisor  of  all  development  work.  In 
others  a  machine  foreman  has  been  employed  for  this 
purpose,  and  his  duties  are  similar  to  those  of  the  drill 
instructors  and  development  bosses.  The  question  as  to 
whether  instructions  should  be  given  by  a  drill  in- 
structor, development  boss  or  machine  foreman  should  be 
decided  according  to  conditions  at  the  particular  mine. 


STANDARD  MACHINE  DRILL  ROUNDS  29 

RESULTS  ATTENDING  ADOPTION  OF  STANDARD  ROUND 
HAVE  JUSTIFIED  EXPERIMENTATION 

Adoption  of  the  standard  round  has  led  to  a  material 
increase  in  the  footage  per  man  shift.  The  amount  of 
ground  drilled  is  usually  removed  in  the  blast,  as  the 
holes  bottom  in  a  vertical  plane  which  leaves  a  square 
face  for  the  next  set-up.  Since  the  introduction  of  the 
standard  round,  the  size  and  shape  of  drifts  are  more 
uniform,  and  the  men  are  careful  not  to  drill  wild  holes 
and  break  a  lot  of  unnecessary  ground  in  the  back  or 
sides,  as  they  formerly  did. 

It  has  been  satisfactorily  proved  that  a  machine-drill 
round  need  not  necessarily  be  drilled  according  to  the 
slips  and  breaks  in  the  ground,  as  the  footage  advanced 
by  the  standard  round  has  far  surpassed  that  obtained 
with  a  variable  round  put  down  according  to  the  frac- 
tures and  faults  in  the  face. 

In  drifts  where  the  bonus  system  has  been  instituted, 
the  miners  have  repeatedly  tried  and  failed  to  make  the 
bonus  when  using  the  old  type  of  round,  and  have  found 
that  it  is  possible  to  make  the  required  footage  only 
when  the  standard  round  is  used. 

Abnormal  labor  conditions  and  the  loss  to  the  mines 
of  large  numbers  of  trained  miners  who  have  joined 
the  Army,  have,  during  the  last  year,  detracted  from  the 
results  formerly  obtained  from  the  use  of  the  standard 
type  of  round.  However,  when  normal  conditions  are 
restored,  results  as  good  as  if  not  better  than  those 
formerly  achieved  may  be  confidently  expected. 


Section  III 


Ventilation 
of  Metal  Mines 


IN  THE  early  stages  of  the  development  of  metal 
mines,  all  prospect  work  is  necessarily  directed 
toward  finding  ore,  and  little  or  no  consideration  is 
given  to  the  subject  of  ventilation  until  the  orebodies  are 
discovered.  In  prosecuting  this  work,  natural  ventilation 
is  utilized  to  its  fullest  extent  until  all  its  possibilities 
are  exhausted.  It  is  then  generally  supplemented  by 
the  installation  of  a  few  small  blowers.  These  answer 
the  purpose  temporarily,  until  the  prospect  develops  into 
a  mine,  when,  in  the  course  of  time,  the  natural  ventila- 
tion frequently  proves  insufficient,  and  a  scheme  of 
mechanical  ventilation  must  be  worked  out. 

Much  has  been  accomplished  in  solving  the  ventila- 
tion problems  in  coal  mines,  but  it  is  only  recently  that 
this  subject  has  received  serious  consideration  by  metal 
miners.  In  the  past,  practically  all  mines  were  ven- 
tilated by  natural  means,  and  the  miners  were  expected 
to  do  their  best  under  the  varying  conditions,  which 
are  always  poorest  during  the  summer,  as  is  evidenced 
by  the  decreased  labor  efficiency  in  the  summer  months. 

It  became  increasingly  apparent  in  recent  years  that 
conditions  of  natural  ventilation  were  inadequate  to  meet 


VENTILATION  OF  METAL  MINES  31 

the  needs  of  the  metal  mines  of  the  Southwest,  and  the 
question  arose  as  to  what  extent  improvements  could 
be  made  in  ventilation  by  mechanical  means  in  order 
to  bring  about  the  desired  change  in  the  temperature, 
humidity,  velocity  and  volume,  and  as  to  what  should 
constitute  a  "good  working  atmosphere."  No  readings 
had  been  made  to  determine  the  volume  of  air  entering 
or  leaving  a  mine;  the  necessary  quantity  of  air  per 
man  per  minute;  to  what  extent  the  humidity  would  be 
increased  from  the  time  the  air  entered  the  mine  until 
it  reached  the  different  outlets;  the  amtmnt  of  air 
needed  to  clear  away  the  smoke  during  ordinary  blast- 
ing in  the  average  mine  workings ;  or  the  total  friction 
losses,  due  to  the  extreme  irregularities  of  the  workings, 
which  may  be  termed  "the  mine  resistance." 

In  some  states  standard  requirements  for  ventilation 
in  mines  are  prescribed  by  law,  but,  in  general,  this  is 
left  to  the  discretion  of  the  operators.  The  Arizona 
mining  law  says  that  "the  total  quantity  of  carbon 
dioxide  present  in  the  air  shall  not  exceed  0.25%  by 
volume,  except  that  at  any  place  where  firing  of  ex- 
plosives has  been  done  a  higher  percentage  of  carbon 
dioxide  shall  be  permissible  for  a  reasonable  length  of 
time  after  the  last  explosion.  .  .  ."  The  Anthracite 
Mine  Law  of  Pennsylvania  specifies  a  minimum  quantity 
of  200  cu.ft.  of  air  per  man  per  min.,  and  the  law 
further  stipulates  that  the  amount  of  air  in  circulation 
shall  be  sufficient  "to  dilute,  render  harmless,  and  sweep 
away  smoke  and  noxious  or  dangerous  gases,"  proving 
that  even  in  coal  mines,  where  the  problems  of  ventila- 
tion have  not  the  intricacies  found  in  metal  mines,  no 
fixed  standard  has  been  adopted  upon  which  to  base 
figures  for  a  "good  working  atmosphere."  This,  then, 
was  the  problem  that  confronted  the  ventilating  en- 
gineer. 

There  are  two  methods  by  which  the  degree  of  ventila- 
tion may  be  determined :  (a)  According  to  the  quantity 
of  pure  air  per  man  per  min.  entering  the  mine; 
(b)  by  determining  the  amount  of  impurity  present 
by  making  a  chemical  analysis  of  the  air.  The  quantity 


32  STANDARDIZATION  OF  MINING  METHODS 

standard  is  less  expensive  and  more  practicable,  and 
is  the  method  most  generally  used.  The  quality  stand- 
ard is  expensive,  and  its  application  is  necessary  only 
in  exceptional  cases.  It  has  only  a  remote  bearing  on 
the  efficiency  of  the  men,  but  occasionally  it  is  found 
advisable  to  have  accurate  determinations  made  on 
several  samples  of  mine  air. 

HUMIDITY  CAUSES  MANY  MINES  TO  SEEM  HOT 

After  a  large  number  of  readings  had  been  taken,  it 
was  found  that  in  many  mines,  though  the  temperature 
was  not  high,  the  humidity  was  excessive,  the  velocity 
low  and  the  volume  small.  A  stope  having  a  tem- 
perature of  80°  F.  and  a  humidity  of  99%  seemed  ex- 
cessively hot,  though  another  stope  with  the  same  tem- 
perature and  a  humidity  of  75%  was  comparatively 
cool.  This  was  affected  somewhat  by  the  velocity  and 
volume  of  the  air  in  the  working  places.  The  greater 
the  velocity  and  volume  (provided  the  temperature  and 
humidity  were  constant),  the  cooler  the  stope  appeared 
to  be.  For  example,  the  following  readings  were  taken 
in  a  stope  that  was  evidently  in  need  of  better  ventila- 
tion: Velocity,  10  ft.  per  min.  (approximately)  ;  volume, 
50  cu.ft.  per  min.  (approximately)  ;  temperature,  84° 
F.,  and  humidity,  96  per  cent. 

A  small  5-hp.  blower  was  forcing  air  into  this  stope. 
The  miners  were  uncomfortable  and  complained  of  the 
excessive  heat.  Five  months  later,  after  a  new  ventilat- 
ing system  had  been  installed,  the  following  readings 
were  made  in  the  same  stope:  Velocity,  100  ft.  per  min.; 
volume,  500  cu.ft.  per  min.;  temperature,  84°  F.,  and 
humidity,  90%.  The  miners  mentioned  happened  to 
be  working  in  this  stope  on  that  date,  and  one  miner 
remarked,  "The  stope  is  not  nearly  as  hot  as  it  used  to 
be,  and  we  can  work  much  better."  The  men  did  not 
sweat  excessively  in  this  atmosphere,  and  the  greater 
comfort  that  they  experienced  was  due  to  the  increase 
in  velocity,  which  also  means  an  increase  in  volume, 
with  lower  humidity,  and  not  to  the  temperature,  as 
it  was  the  same  in  both  cases. 

After  a  number  of  experiments  had  been  made,  the 


VENTILATION  OF  METAL  MINES  33 

following  specifications  were  decided  upon  as  constitut- 
ing a  "good  working  atmosphere":  Temperature,  78° 
F.;  humidity,  80%;  velocity,  125  ft.  per  min.,  and  vol- 
ume, 350  cu.ft.  per  man  per  min.  Though  there  were 
some  places  in  the  mines  where  the  velocity  and  volume 
were  much  higher  than  this,  there  were  others  in  which 
they  were  lower;  consequently,  this  was  taken  as  an 
average  of  all  the  velocities  and  volumes  in  working 
places  in  the  mines  in  which  the  tests  were  made.  It 
was  found  that  in  an  atmosphere  of  this  character  men 
could  be  expected  to  perform  a  fair  day's  work,  and  that 
smoke  and  gases  from  the  mine  were  diluted  and  finally 
carried  off.  This  working  atmosphere  has  been  found  to 
be  particularly  suitable  for  mines  in  the  Southwest. 

CAREFUL  STUDY  MUST  PRECEDE  INSTALLATION 
OF  MECHANICAL  VENTILATION  EQUIPMENT 

In  mines  where  mechanical  ventilation  is  required 
painstaking  consideration  should  be  given  as  to  the  kind 
of  atmosphere  which  it  is  advisable  to  establish.  When 
this  has  been  determined,  a  thorough  study  of  the  mine 
and  workings  should  be  made  in  order  to  obtain  definite 
information  concerning  underground  conditions.  In 
order,  therefore,  to  estimate  the  amount  of  air  which  will 
be  necessary  for  the  desired  working  atmosphere,  the 
following  factors  should  be  taken  into  account :  Number 
of  men  and  animals  in  each  district,  the  production 
of  C02  or  other  gases,  relative  humidity,  temperature, 
amount  of  explosives  used,  the  distance  from  currents 
of  good  air,  the  number  of  lights,  air  leakage,  friction 
of  the  air  currents,  number  of  splits  of  the  air  cur- 
rent, and  method  of  distribution. 

In  mines  where  there  is  considerable  square-setting 
in  ores  containing  much  sulphur,  and  where  a  large 
amount  of  timber  is  used  for  doubling  up,  bulkheading 
and  similar  work,  a  greater  volume  of  air  will  be  re- 
quired to  maintain  the  same  good  working  atmosphere 
than  in  mines  where  the  cut-and-fill  system  is  used,  with 
its  usual  limited  amount  of  timber.  The  same  may  be 
said  of  top-slice  stopes.  In  top-slicing,  there  is  a  large 
timbered  mat  directly  over  the  men,  which  usually  cuts 


34  STANDARDIZATION  OF  MINING  METHODS 

off  any  outlet  to  surface.  Stopes  of  this  character 
are  more  difficult  to  ventilate,  and  take  more  air,  than 
shrinkage  stopes,  which  have  practically  no  timber  and 
where  the  ground  is  so  firm  that  connections  above 
the  usual  workings  are  easily  maintained  as  outlets  for 
the  air.  In  caving  methods  using  the  incline-raise  sys- 
tem and  extensive  grizzly  levels,  it  is  necessary  to  do  a 
large  amount  of  blasting,  first  in  drawing  the  ore  down 
to  the  grizzly  level,  and,  second,  in  breaking  boulders  on 
the  grizzly.  This  naturally  results  in  a  large  amount  of 
powder  smoke,  and  it  is  consequently  necessary  to  pro- 
vide for  an  unusual  quantity  of  air  in  order  to  main- 
tain a  good  working  atmosphere. 

VENTILATING  SYSTEMS  MAY  AID  FIRE  FIGHTING 

Ventilating  systems  have  been  planned  in  a  few  mines 
and  installed  primarily  as  safety  measures  to  permit 
immediate  attack  being  made  on  possible  mine  fires,  and 
only  secondarily  as  aids  to  ventilation,  the  natural  air 
currents  having  proved  fairly  satisfactory.  In  most 
cases,  however,  the  direct  object  for  which  a  mechanical 
ventilating  system  is  installed  is  to  improve  the  at- 
mosphere, and  its  use  in  fire-fighting  is  given  only 
secondary  consideration. 

By  far  the  most  economical  method  of  installing  a 
ventilating  system  is  to  work  out  a  comprehensive 
scheme  of  mechanical  ventilation  (using  the  natural 
air  currents  wherever  possible),  in  connection  with  the 
development  of  new  orebodies,  so  that,  when  the  ore- 
bodies  have  reached  the  producing  stage  the  necessary 
air  connections  will  have  been  made.  Ventilation  should 
go  hand  in  hand  with  stoping,  both  being  planned  simul- 
taneously, so  that,  when  the  latter  is  begun,  the  ventilat- 
ing system  will  also  be  in  operation,  making  it  possible 
for  the  men  to  perform  their  duties  in  good  air. 

One  of  the  objections  to  installing  a  ventilating  sys- 
tem as  the  orebody  is  developed  is  that,  if  the  installa- 
tion is  delayed,  it  may  be  found  possible  to  get  along 
with  the  natural  ventilation.  However,  in  the  majority 
of  cases  this  can  easily  be  foreseen,  and  in  practically 
all  deep  mines  mechanical  ventilation  is  a  necessity. 


VENTILATION  OF  METAL  MINES  35 

It  always  costs  more  to  put  in  such  a  system  afterward, 
when  many  new  connections  must  be  Driven,  than  it 
does  if  planned  right  in  the  first  place  with  the  develop- 
ment of  the  workings. 

SEPARATE  SYSTEM  FOR  DEVELOPMENT  WORK 

Frequently,  after  a  ventilating  system  has  been  in- 
stalled, the  necessity  for  its  expansion,  coincident  with 
the  stoping,  is  overlooked,  and,  while  the  stoping  con- 
tinues, nothing  is  done  toward  the  ventilation,  so  that 
in  course  of  time,  as  the  workings  increase,  it  loses  its 
effect  and  fails  to  serve  the  purpose  for  which  it  was 
designed.  It  is  therefore  highly  important  that  the 
ventilating  system  be  expanded  to  meet  the  constant 
changes  and  progress  in  stoping. 

There  are  two  systems  of  mine  ventilation,  the  exhaust 
and  pressure.  In  the  exhaust  system,  the  fan  is  usually 
on  the  surface,  and  exhausts  the  vitiated  air  from  the 
mine  while  the  fresh  air  enters  through  the  working 
shafts  and  flows  in  to  take  its  place.  The  pressure 
system  usually  has  the  fan  placed  underground,  near 
the  main  downcast  shafts,  which  should  also  be  the 
working  shafts,  and  forces  the  air  through  the  work- 
ings by  putting  the  entire  mine  under  pressure,  the  air 
finding  its  way  out  through  shafts,  raises,  or  ground 
caved  and  broken  to  the  surface.  Most  installations 
in  the  Southwest  are  of  this  latter  type,  because  shafts 
at  many  of  the  largest  mines  are  all  operating  shafts 
and  cannot  be  spared  for  ventilation  purposes  only. 
It  is,  therefore,  impracticable  to  put  a  suction  fan  on  the 
surface  at  an  operating  shaft.  The  placing  of  fans  un- 
derground has  given  satisfaction,  nevertheless,  as  owing 
to  the  use  of  double  doors,  there  has  been  practically 
no  short-circuiting  of  the  air. 

CORRECT  DISTRIBUTION  OF  AIR  PRINCIPAL  OBJECT 

The  mere  installation  of  mine  fans,  however,  does 
not  constitute  a  complete  system  of  mechanical  ventila- 
tion. The  proper  coursing  and  distribution  of  air 
through  the  workings  is  the  only  effective  test  of  the 
efficiency  of  a  ventilating  system.  In  a  few  mines  large 


36  STANDARDIZATION  OF  MINING  METHODS 

fans  have  been  installed  without  much  attention  being 
given  to  this  important  consideration,  and  a  thorough 
study  of  the  workings  would  show  that  better  ventilation 
in  general  could  be  obtained  with  half  the  number  of 
fans,  provided  the  mining  features  that  are  involved 
received  proper  attention.  This  would  not  only  improve 
the  ventilation  but  would  materially  reduce  the  cost  of 
the  ventilating  system. 

The  capacity  of  fans  which  have  been  installed  varies 
from  about  10,000  to  200,000  cu.ft.  of  air  per  min.,  the 
pressure  or  suction  being  from  1  in.  to  5  in.  The  large- 
capacity  fans  of  from  250,000  to  400,000  cu.ft.  of  air 
per  min.,  which  are  found  in  coal  mines,  are  impracti- 
cable in  metal  mines,  except  in  a  few  instances,  because 
the  total  intake  or  outlet  areas  of  shafts  in  metal  mines 
are  not  nearly  equal  to  those  in  coal  mines. 

Some  mining  companies  have  installed  reversible  fans, 
the  idea  being  to  reverse  the  fan  in  case  of  fire  in  a 
downcast  shaft.  However,  after  consideration  of  the 
35  mine  fires  which  have  occurred  in  the  Southwest 
during  the  last  seven  years,  I  find  that  in  no  case  was 
it  necessary  to  reverse  the  fan.  In  fact,  in  nearly  every 
instance  the  danger  would  have  been  increased,  because 
the  men  expect  the  air  to  keep  moving  in  a  certain 
direction,  and,  if  the  air  currents  should  be  changed 
without  their  knowledge,  there  would  be  danger  of  the 
miners  being  caught  in  gas. 

SIMPLEST  SYSTEM  USES  ONE  CENTRAL  INSTALLATION 

The  most  inexpensive  ventilating  system,  using  pres- 
sure, consists  of  one  central  installation  (either  on  sur- 
face or  underground)  with  large  intake  and  a  dis- 
charge into  diverging  drifts,  from  which  the  air  is  fur- 
ther discharged  into  still  larger  areas.  In  the  suction 
system,  the  blower  is  usually  on  the  surface,  and  all 
drifts  from  the  workings  should  converge  to  the  central 
intake  at  the  fan,  through  which  the  air  is  drawn  to 
the  surface  and  discharged.  One  central  installation, 
however,  using  either  pressure  or  suction,  ordinarily 
could  not  supply  adequately  the  scattered  workings, 
which  require  in  most  mines  from  one  to  four  additional 


VENTILATION  OF  METAL  MINES  37 

installations  to  be  satisfactorily  ventilated.  Occasion- 
ally, "booster"  fans  are  used  as  an  aid  to  the  general 
ventilating  system.  Two  or  three  mines  are  sometimes 
so  intimately  connected  that,  in  order  to  work  out  a 
ventilating  system  for  one,  it  is  necessary  to  work  it 
out  for  all.  In  some  instances  a  combination  of  both  the 
pressure  and  exhaust  systems  is  adopted. 

The  installation  of  the  mine  fans  is  the  smallest  part 
of  the  cost  of  putting  in  a  ventilating  system.  By  far 
the  greater  expense  is  incurred  in  the  necessary  changes 
in  the  mine,  such  as  cutting  a  blower  station  for  mine 
fans  (in  case  they  are  underground)  ;  driving  drifts 
and  raises  to  allow  sufficient  air  to  pass  to  ventilate 
the  stopes;  erecting  doors  in  suitable  drifts  and  cross- 
cuts and  putting  in  stoppings  to  cut  off  old  workings 
and  leaks  which  would  impair  the  efficiency  of  the  ven- 
tilating system,  and  making  other  similar  and  necessary 
alterations. 

DEVELOPMENT  AND  OTHER  WORKINGS  MUST  ALSO 
BE  VENTILATED 

The  systems  described  above  are  for  the  purpose  of 
ventilating  the  major  portion  of  the  workings,  which 
comprise  about  80%  of  the  mine;  the  remaining  20% 
must  be  taken  care  of  in  some  other  way.  This  20% 
generally  consists  of  the  prospect  and  development  work, 
such  as  drifts,  raises  and  winzes,  and  must  be  done  in 
advance  of  the  usual  stoping  operations.  For  this 
work  it  is  necessary  to  use  an  auxiliary  ventilating 
system,  which  should  be  standardized  wherever  pos- 
sible. 

When  the  headings  are  being  driven  in  such  work  the 
exhaust  air  from  machine  drills  is  used  to  furnish  the 
necessary  ventilation.  No  compressed  air  is  required 
when  machines  are  running.  The  exhaust  of  the  average 
machine  gives  approximately  100  cu.ft.  of  ventilating 
air  per  minute.  However,  it  is  well  known  that  this  is 
not  the  purest  air,  as  it  is  vitiated  somewhat  by  the  oil 
which  vaporizes  in  the  machine  and  comes  out  with 
the  exhaust.  After  blasting,  the  full  head  of  compressed 
air  is  usually  turned  on  to  clear  out  the  heading. 


38 


STANDARDIZATION  OF  MINING  METHODS 


After  drifts,  raises,  or  winzes  have  been  driven  a 
certain  distance,  a  point  is  reached  at  which  the  com- 
pressed air  is  insufficient,  and  it  then  becomes  necessary 
to  install  artificial  ventilation.  An  air  jet,  for  example 
the  Koerting-nozzle  type,  which  uses  a  small  amount 


l<- First  Year- 


I        CHART  3 
•>H Second    Year- 


•>t<- Third  Year- 


FIG.  1.    CHART  1  ILLUSTRATES  TOTAL  VOLUME  OF  AIR  MOVED 
PER  MINUTE.    CHART  2,  TOTAL  COST  OF  VENTILA- 
TION.   CHART  3,  TONNAGE  PRODUCED 

of  compressed  air,  at  the  same  time  having  a  strong 
suction  so  as  to  draw  a  large  amount  of  fresh  air 
around  the  nozzle  and  force  it  through  the  ventilating 
pipe,  is  generally  found  sufficient.  (One  cu.ft.  of  com- 
pressed air  will  furnish  approximately  18  cu.ft.  of  ven- 
tilating air.)  As  raises  and  occasional  winzes  are  driven 
only  about  100  ft.,  an  air  jet  supplying  air  for  10-in. 
pipe  should  provide  ample  ventilation  under  average 


VENTILATION  OF  METAL  MINES  39 

conditions.  Drifts  are  usually  driven  longer  distances, 
and  should  be  provided  with  electric  blowers.  In  gen- 
eral, a  10-in.  blower,  designed  by  standard  manufac- 
turers, using  a  2£-hp.  motor  (both  blower  and  motor 
mounted  on  one  base)  is  suitable. 

JETS  AND  BLOWERS  MUST  BE  PROPERLY  PLACED 

The  position  of  air  jets  and  blowers  is  important. 
If  they  are  placed  within  the  drift  or  raise  to  be  ven- 
tilated, air  will  merely  circulate  between  the  blower  and 
the  end  of  the  pipe.  They  should  be  situated  outside  or 
have  the  intake  outside  of  the  drifts  and  raises.  The 
pipe  should  reach  to  the  working  face,  so  that  it  will  not 
be  necessary  to  use  compressed  air.  Before  blasting, 
the  sections  near  the  face  should  be  taken  down  and 
put  where  they  will  not  be  injured. 

After  the  drift  has  progressed  about  3000  ft.,  the 
blower  should  be  provided  with  a  reversing  attachment 
in  order  that  it  may  be  reversed  to  clear  the  smoke  away, 
and  after  that  be  run  as  a  pressure  fan,  to  furnish  good 
air  at  the  heading.  In  exceptional  cases,  principally  in 
tunnel  work,  where  speed  is  important,  two  blowers 
should  be  used,  one  for  pressure  and  the  other  for  suc- 
tion. This  permits  almost  continuous  work  at  the 
heading. 

VENTILATION  MAY  BE  STANDARDIZED 
With  the  introduction  of  mechanical  ventilation,  it 
has  been  found  that  the  atmosphere  in  mines  can  be 
standardized  instead  of  having  shifting  and  uncertain 
currents  of  natural  ventilation.  It  has  also  been  dem- 
onstrated that  this  standard  atmosphere  is  well  within 
the  economic  limit  and  that  it  pays  to  ventilate  a  mine 
by  increasing  the  amount  of  air  until  such  standard 
conditions  are  reached. 

The  velocity  of  air  currents  in  working  drifts  has 
been  brought  up  to  1200  cu.ft.  per  min.,  and  in  excep- 
tional cases  to  2000  cu.ft.  The  former  figure  approaches 
the  economic  limit  at  most  mines  where  power  cost  is 
a  large  item,  and  the  latter  should  be  set  as  a  max- 
imum for  safety.  The  "good  working  atmosphere"  men- 


40 


STANDARDIZATION  OF  MINING  METHODS 


tioned  previously  has  been  tried  out  in  a  number  of 
mines  in  the  Southwest  for  a  period  of  over  five  years 
and  has  proved  entirely  satisfactory  as  a  standard  for 
conditions  existing  in  this  part  of  the  country. 

COST  SHEETS  PROVE  VALUE  OF  GOOD  Am 

Actual  figures  showing  a  reduction  in  costs  and  a  de- 
crease in  consumption  of  compressed  air  prove  the  value 
of  such  an  installation,  and  point  to  the  results  that 


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First  Year' "^H Second"  Year >t< Third  Year 


FIG.  2.    CHART  4  ILLUSTRATES  DECREASE  IN  COMPRESSED  AIR 

USED  AFTER  INSTALLATION  OF  VENTILATION  SYSTEM. 

CHART  5,  INCREASE  IN  TONS  PER  MAN  PER  SHIFT. 

CHART  6,  DECREASE  IN  COST  OF  MINING 

might  possibly  be  obtained  were  the  standard  made  still 
higher  by  securing  a  lower  humidity,  lower  temper- 
ature and  greater  volume  of  air  per  man  per  minute. 
The  accompanying  charts  show  the  results  obtained  by 
installing  a  well-planned  mechanical  ventilating  system, 
and  cover  a  period  of  two  and  a  half  years. 


VENTILATION  OF  METAL  MINES  41 

Chart  No.  1  shows  the  total  volume  of  air  moved  per 
minute,  and  Chart  No.  2  the  total  cost  of  ventilation. 
In  Chart  No.  3  it  will  be  seen  that  after  the  date  of  the 
installation  of  the  mechanical  ventilating  system  there 
was  a  marked  increase  in  tonnage  until  the  latter  part 
of  the  second  year,  when,  owing  to  unusual  conditions, 
production  was  much  curtailed.  However,  in  the  early 
part  of  the  third  year  the  tonnage  again  increased,  and 
in  June  there  was  an  increase  of  4000  tons  over  that 
in  January  of  the  first  year. 

Chart  No.  4  illustrates  the  decrease  in  the  quantity 
of  compressed  air  used,  owing  to  the  installation  of  the 
ventilating  system.  The  curve  shows  the  total  amount 
of  compressed  air  needed  both  for  ventilation  and  ma- 
chine drills.  This  accounts  for  the  rise  in  the  curve 
from  November  of  the  second  year  to  June  following,  as 
the  tonnage  increased  from  10,500  per  month  to  18,500 
tons.  Consequently  more  machines  were  used  to  break 
the  ore  represented  in  this  added  tonnage. 

Chart  No.  5  shows  the  increase  in  tons  per  man  per 
shift.  This  is  obtained  by  dividing  the  daily  tonnage 
by  the  total  number  of  men  employed  in  the  mine.  The 
mining  method  used  in  this  particular  mine  was  prac- 
tically all  square  setting,  and  all  the  ore  had  to  be  sorted. 
Only  one  stope  in  the  entire  mine  was  worked  by  the 
cut-and-fill  method.  The  increase  after  the  new  venti- 
lating system  was  installed  was  from  about  2£  tons  to 
7  tons,  or  approximately  180  per  cent. 

Chart  No.  6  illustrates  the  decrease  in  the  cost  of 
mining  the  ore,  and  an  average  for  the  first  seven 
months  of  the  first  year,  compared  with  an  average  of 
the  seven  months  preceding  June  of  the  third  year, 
shows  a  drop  of  from  $1.57  to  $0.85,  or  a  decrease  of 
$1.02  per  ton. 

Large  fans  are  designed  for  the  capacity,  pressure 
or  suction,  as  well  as  for  the  elevation  where  they  are  to 
be  operated.  Regarding  small  blowers,  however,  a 
standard  size  and  design  of  electric  motor,  blower  and 
ventilating  pipe  should  be  decided  upon.  A  2£-hp.  motor, 
connected  to  a  10-in.  blower  and  10-in.  ventilating  pipe, 
is  usually  sufficient.  It  is  important  that  a  standard  be 


42  STANDARDIZATION  OF  MINING  METHODS 

selected,  as,  for  example,  the  one  mentioned  above,  as 
there  are  many  mines  where  8-in.,  10-in.  and  12-in. 
ventilating  pipe,  with  different  types  of  blowers  and 
complementary  apparatus,  may  be  found  in  use  at  the 
same  time.  This  is  likely  to  cause  confusion  and  delay 
because  of  attempts  to  attach  pipe  of  the  wrong  size 
to  blowers,  and  in  other  ways. 

Either  metal  pipe  or  canvas  tubing  may  be  used  for 
ventilating  purposes.  Metal  pipe  has  been  found  satis- 
factory and  is  in  general  use  in  mines  throughout  the 
Southwest.  When  properly  put  up,  with  joints  that  are 
carefully  sealed  with  burlap  and  tar,  it  requires  no 
further  attention,  as  joints  of  this  character  prevent 
leakage,  and  the  angle  at  which  the  pipe  is  hung  pre- 
vents water  lodging  in  it.  It  stands  up  well  under  min- 
ing conditions,  and  when  the  usual  precautions  are  taken 
to  remove  the  lengths  near  the  face  before  blasting,  the 
pipe  is  usually  not  materially  damaged  by  the  small 
rocks  which  occasionally  strike  it. 

Canvas  tubing  has  the  advantage  of  being  more  easily 
handled,  as  it  can  be  taken  down  the  shaft  and  hung 
in  less  time  and  at  less  expense  than  iron  piping,  and 
it  is  also  more  flexible  in  rounding  curves,  as  iron  pipe 
needs  an  elbow  at  every  turn.  There  is,  however,  a 
question  as  to  how  its  durability  will  compare  with  that 
of  iron  tubing  under  ordinary  mining  conditions.  The 
difficulty  arising  through  water  gathering  in  it  is  also 
generally  experienced,  making  frequent  attention  neces- 
sary. In  some  of  my  experiments  underground,  when 
the  miners  were  ready  to  blast  they  would  take  down 
the  canvas  tubing,  coil  it  up  along  the  drift,  and  move 
it  back  a  reasonable  distance.  At  times  some  of  the 
smaller  pieces  from  the  blast  flew  back  and  cut  holes  in 
the  canvas,  which  damaged  it  considerably,  and  in  addi- 
tion, the  tubing  was  subjected  to  the  ordinary  wear  and 
tear  of  rolling  it  along  the  drift  and  coiling  it  up  in 
places  where  there  was  frequently  mud  and  water. 

Some  time  ago  experiments  with  small  blowers  and 
different  kinds  and  sizes  of  ventilating  pipe  in  100  and 
200-ft.  lengths  were  made  under  my  supervision.  It 
was  found  that  the  velocity  and  volume  delivered  at  the 


VENTILATION  OF  METAL  MINES 


43 


end  of  200  ft.  of  10-in.  canvas  tubing  were  consider- 
ably less  than  when  delivered,  under  similar  conditions, 
at  the  end  of  200  ft.  of  10-in.  iron  pipe.  This  made  it 
evident  that  in  order  to  deliver  the  same  volume  of  air 
at  the  working  face  through  canvas  tubing  that  it  is 
possible  to  deliver  through  the  iron  pipe,  it  is  necessary 
to  have  a  much  larger  size  of  canvas  tubing,  or  else,  if 


FIG.  3.    DOOR  FOR  BOTH  HAND  AND  MULE  TEAM 

the  same  size  tubing  be  used,  the  blower  must  be  speeded 
up  or  a  larger  blower  be  installed.  In  places  where  the 
cost  of  power  must  be  considered,  the  extra  expense 
is  important.  Metal  rings  inserted  in  the  canvas  tub- 
ing at  frequent  intervals  restore  more  nearly  the  con- 
dition effected  through  the  use  of  the  iron  pipe,  as  they 
help  to  support  the  canvas,  which  otherwise  would  have 


44 


STANDARDIZATION  OF  MINING  METHODS 


only  the  air  pressure  as  support.  However,  all  these 
improvements  add  to  the  cost  of  the  tubing,  and  there 


I*       *      .^  j  ,t         ^        .  __^      ,,.,.„,,,.,       e    f 


is  some  question,  when  all  is  considered,  whether,  even 
under  these  circumstances,  it  would  prove  as  efficient  as 
iron  piping. 


VENTILATION  OF  METAL  MINES  45 

In  the  mines  in  some  districts  stoppings  are  called 
bulkheads.  These  are  used  to  seal  off  dead  workings, 
air  leaks,  or  drifts  and  raises  leading  to  stopes  which 
are  not  in  operation.  A  stopping  which  may  be  adopted 
as  standard  should  be  constructed  as  follows:  Suppose 
a  drift  is  to  be  bulkheaded.  The  ground  is  first  cut  out 
around  the  drift  where  the  stopping  is  to  be  placed. 
After  that,  4  x  6-in.  posts  are  set  up,  three  feet  apart, 
across  the  drift.  Then  1  x  12-in.  boards  are  nailed  to 
the  posts,  making  a  partition.  Metal  lath  is  tacked  on 
to  the  boards.  In  case  metal  lath  is  not  available,  double 
wire  netting  with  small-diameter  openings  may  be  used. 
A  fine  coating  of  cement,  §-in.  thick,  put  on  either  by 
hand  or  with  the  cement  gun,  is  then  applied.  If  only 
old  workings  are  to  be  sealed  off,  and  it  is  desired  that 
some  air  should  be  allowed  to  pass  through  them,  the 
cement  and  boards  in  the  stopping,  near  the  center, 
should  be  omitted.  For  example,  a  space  2  x  2  ft.  should 
be  left,  but  the  wire  netting  should  cover  the  entire  sur- 
face. Should  it  be  found  desirable  to  seal  up  this  space 
later,  a  cement  coating  may  be  put  over  the  wire  netting. 

STANDARDIZED  DOORS  SHOULD  BE  USED 

All  doors  should  be  of  standard  size.  In  general, 
two  standards  are  necessary.  They  are  illustrated  in 
Fig.  3  and  Fig.  4.  In  Fig.  3  is  shown  the  design  of  a 
door  for  both  hand  and  mule  tram.  Fig.  4  shows  a  door 
for  use  in  motor-haulage  drifts.  In  the  latter  sketch  de- 
tails such  as  handles,  hinges,  weights,  cable,  pulleys 
and  canvas  are  given.  Fig.  4  also  illustrates  an  air- 
controlled  arrangement  to  be  attached  to  the  same  door, 
so  that  motor  trains  may  pass  throughout  without 
stopping. 

The  Canton  automatic  door  has  been  installed  in  many 
mines  and  has  given  satisfaction  when  used  against  low 
pressures.  Double  doors  should  be  placed  in  all  im- 
portant drifts  where  it  is  necessary  to  keep  up  either  a 
high  pressure  or  suction  in  order  to  force  the  air  from 
the  drift  into  more  distant  mine  workings. 

Regulator  doors  are  constructed  as  are  the  doors,  al- 
ready mentioned,  except  that  openings  are  cut  in  them 


46  STANDARDIZATION  OF  MINING  METHODS 

and  slides  built  in  to  regulate  the  flow  of  air.  In  this 
manner  the  volume  of  air  to  any  area  can  be  regulated 
so  that  all  workings  may  receive  their  proportion  of 
the  air  supply. 

The  necessary  equipment  in  a  mechanical  ventilating 
system,  such  as  doors,  frames,  hinges,  weights,  auto- 
matic arrangements,  small  motors,  small  blowers,  and 
ventilating  pipe,  should  all  be  standardized.  Standard- 
ized manways,  timber  compartments  and  chutes  in  raises 
should  also  be  designed  as  an  aid  to  the  ventilating 
system. 

In  order  to  maintain  the  maximum  production,  with 
a  corresponding  high  standard  in  the  quality  of  the 
work,  it  is  absolutely  necessary  that  every  working 
place  should  have  a  good  working  atmosphere,  and  that 
the  ventilation  should  be  so  kept  up  with  the  progress 
of  the  work  that  the  men  may  continue  to  perform  their 
duties  in  health  and  comfort.  Mechanical  ventilating 
systems  which  have  been  designed  with  careful  study 
and  are  now  in  operation  have  fully  justified  the  cost 
of  their  installation,  as  evidenced  by  the  increase  in 
tons  per  man  per  shift  and  the  decrease  in  cost.  In 
mines  where  such  a  system  has  been  carefully  worked 
out  and  conditions  have  been  standardized  as  much  as 
possible,  there  has  always  been  a  great  saving  in  the 
amount  of  compressed  air  used.  In  fact,  in  some  cases 
the  economy  in  this  item  alone  has  more  than  balanced 
the  cost  of  installation. 

Conditions  can  be  made  standard  in  mines  only  where 
a  complete  mechanical  ventilating  system  is  in  opera- 
tion. Fewer  men  will  be  gassed  in  headings  when  stand- 
ard equipments  are  available  and  installed  before  the 
atmosphere  becomes  dangerous.  There  will  also  be  less 
decay  of  mine  timber.  Further  experimental  work  may 
suggest  the  advisability  of  raising  the  standard  of 
mine  atmosphere. 


Section  IV 


Explosives 


r|  MIE  dangers  incidental  to  the  storage  and  han- 
dling of  explosives  are  the  cause  of  much  concern 

JL  to  members  of  mining  organizations.  Apart  from 
unavoidable  hazards  and  fatal  and  serious  accidents  due 
to  carelessness,  the  injurious  effects  produced  by  large 
quantities  of  noxious  gases  resulting  from  the  explo- 
sion of  dynamite  must  be  considered.  Many  serious 
injuries  have  been  sustained  by  men  who  are  gassed. 

All  operations  connected  with  the  handling  and  use 
of  explosives  should  be  standardized.  This  would  be  of 
considerable  help  in  eliminating  many  of  the  regrettable 
accidents  which  are  constantly  occurring,  and  would 
tend  to  reduce  the  quantity  of  noxious  gases,  produced 
by  the  explosives,  to  a  minimum. 

When  a  carload  of  powder  is  received  at  the  mines, 
it  is  necessary  to  have  it  unloaded  and  stored  on  the 
surface.  Great  care  should,  of  course,  be  exercised  in 
its  transportation  to  the  magazine,  and  provision  made 
for  the  different  kinds  of  powder  stored  in  one  place, 
so  that  there  may  be  no  confusion  between  low-  and 
high-strength  explosives.  To  prevent  this,  the  magazine 
should  be  divided  into  a  number  of  compartments,  each 
being  properly  labeled  for  the  different  kind  and 
strength  of  powder  which  is  to  be  stored  in  it.  The 
magazine  should  be  well  ventilated,  to  avoid  the  powder 
being  kept  in  an  atmosphere  where  the  humidity  is 


48  STANDARDIZATION  OF  MINING  METHODS 

high,  and  should  preferably  be  constructed  as  a  chamber 
driven  into  the  hillside,  where  it  will  be  free  from 
shock  and  where  there  will  be  no  possibility  of  a 
chance  rifle  bullet  entering  it.  In  exceptional  cases, 
where  it  is  not  practicable  to  drive  into  the  hillside, 
an  adobe,  cement,  stone,  or  brick  magazine  is  usually 
constructed  in  which  to  store  the  powder.  Adobe 
is  preferable  to  cement,  stone  or  brick,  because,  in 
case  of  an  explosion,  it  will  probably  crumble  and  there 
is  less  danger  of  the  material  used  in  its  construction 
being  broken  up  into  missiles. 


FIG.  1.    EXPLOSIVES  MAGAZINE  IN  HILLSIDE 

The  powder  house  should  have  double  doors,  with 
openings  large  enough  to  admit  a  man's  hand,  so  that 
they  may  be  locked  from  the  inside.  This  is  effectual 
in  preventing  any  one  working  at  the  lock  in  an  en- 
deavor to  pick  or  strike  it  with  a  hammer.  Fig.  1 
is  an  illustration  of  such  a  magazine.  In  this  case 


EXPLOSIVES 


49 


there  is  one  main  adit  leading  into  the  hillside,  closed 
by  double  doors,  locked  from  the  inside.  In  Fig.  2 
a  plan  view  is  given  of  the  parallel  drifts  leading  from 
the  main  tunnel,  showing  the  placing  of  chimney  and  the 
different  compartments  in  the  magazine. 

When  the  powder  is  transported  from  the  surface 
magazine  to  the  different  mine  shafts,  it  should  not 
be  left  at  the  collar  of  the  shaft  longer  than  is  abso- 


%>"G.16E  TRACK  j?, 


fiffiMffifl^"' 

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DOOR 


''Entrance  ?o  Magazine 

FIG.  2.    PLAN  OF  POWDER  MAGAZINE 

lutely  necessary,  as  many  accidents  have  occurred 
through  the  explosion  of  powder  there,  before  being 
taken  underground.  This  is  of  the  utmost  importance. 


50 


STANDARDIZATION  OF  MINING  METHODS 


I  have  recently  noted  cases  where  the  powder  is  taken 
to  the  collar  and  left  there  for  an  hour  in  the  morning 
during  the  time  when  the  shift  is  going  to  work. 

Not  more  than  one  day's  supply  of  powder  should, 
of  course,  be  taken  underground.  Powder  should  never 
be  lowered  with  tools  or  supplies  of  any  kind,  as  that 
will  establish  a  practice  which  will  lead  to  the  lower- 
ing of  powder  with  steel  and  similar  material.  At  the 
different  shaft  stations  it  should  be  a  rule  that  the 
powder  men  must  remove  the  powder  from  the  stations 


HOUSE  WHERE  FUSES  ARE  CUT  AND  CAPPED 

immediately  after  it  is  brought  down.  A  boulder  fall- 
ing down  the  shaft  might  accidentally  strike  the  ex- 
plosive. 

From  the  shaft  stations  the  powder  is  taken  to  the 
underground  magazines,  of  which  there  should  be  one 
on  each  level.  These  magazines  should  be  situated 
conveniently  for  all  the  men  on  the  level,  and  at  the 
same  time  far  enough  removed  from  the  blasting  to 
minimize  the  danger  from  shock.  The  magazines  should 


EXPLOSIVES  61 

be  well  ventilated,  and  not  placed  where  the  humidity 
rises  to  more  than  80%  and  the  temperature  is  high. 
They  should  be  used  for  the  storage  of  powder  only 
and  not  as  combination  magazines  for  powder,  tools, 
and  supplies,  as  is  the  practice  in  some  mines.  Each 
magazine  should  be  in  charge  of  a  powder  man,  usually 
called  the  "powder  monkey."  His  duties  are  to  give 
out  the  powder  to  the  drillers  as  they  call  for  it,  and 
to  keep  an  accurate  check  on  the  amount  and  the  place 
where  it  is  to  be  used,  and  this  work  is  usually  com- 
bined with  other  duties,  such  as  checking  up  tools  and 
other  supplies  in  the  tool  house,  which  should  be  situ- 
ated some  distance  from  the  magazine.  The  same  man 
also  attends  to  another  magazine  which  contains  the 
caps  and  fuse. 

Though  it  is  advisable  to  have  the  powder  and  capped 
fuses  taken  to  the  heading  separately,  it  is  impracticable 
in  most  cases,  and  all  miners  coming  to  the  powder 
magazine  should  have  powder  and  fuse  sacks  in  which 
to  carry  their  powder,  fuse,  caps,  and  stemming.  The 
fuse,  caps,  and  stemming  should  be  placed  in  one  sack 
and  the  powder  in  the  other.  These  sacks  should  have 
suitable  handles,  so  that  a  man  can  put  one  on  each 
shoulder  when  climbing  up  a  raise.  Instances  have  been 
known  of  men  tying  fuse  around  sticks  of  powder,  and 
carrying  it  up  ladders  in  this  manner.  Should  the  fuse 
become  loose  and  a  stick  of  powder  drop,  the  results  are 
likely  to  be  serious.  The  caps  and  fuse  should  be  kept 
in  separate  houses  on  the  surface.  In  mines  where  the 
humidity  is  high,  the  fuse  should  not  be  capped  under- 
ground. The  cutting  and  capping  should  be  done  by 
men  who  devote  their  entire  time  to  the  work,  and 
these  operations  can  readily  be  standardized. 

MECHANICAL  FUSE  CUTTER 

A  fuse  cutter  is  preferable  to  a  knife  or  ax,  as  it 
is  necessary  that  the  fuse  be  cut  square  across  and 
to  exact  measurements.  Fig.  3  is  an  example  of  a 
suitable  arrangement.  This  consists  of  a  table  3i  ft. 


52  STANDARDIZATION  OF  MINING  METHODS 

high,  3  ft.  wide,  and  10  ft.  long,  with  a  blade  of  steel, 
foot  pedal,  and  spring  attached.  The  table  is  marked 
into  feet  and  inches,  so  that  the  fuse  may  be  cut  any 
length  up  to  10  ft.  At  one  end  is  a  movable  block, 
set  at  right  angles  to  the  table.  This  regulates  the 
length  of  the  fuse.  The  fuse  spools  are  set  on  pegs, 
just  above  the  table  at  the  opposite  end  to  the  movable 
block.  In  cutting,  the  movable  block  is  placed  at  the 
length  desired,  and  the  fuses,  of  which  the  table  accom- 
modates any  number  up  to  about  25,  are  drawn  along 
the  table  until  the  ends  touch  the  movable  block.  The 
operator  then  steps  on  the  foot  pedal,  which  pulls  the 
steel  blade,  set  at  zero,  down  to  cut  the  lengths  of 
fuse.  On  releasing  the  pedal  the  spring  raises  the 
steel;  the  operator  again  pulls  the  freshly  cut  ends 
to  the  movable  block,  steps  on  the  pedal,  and  repeats 
the  operation.  The  use  of  this  machine  obviates  all 
danger  arising  from  the  fuses  not  being  cut  square. 
After  being  cut,  the  lengths  of  fuse  are  drawn  along 
the  table  a  little  further,  where  they  are  capped. 

CAPPING  OP  FUSES 

In  capping,  the  fuse  should  be  placed  in  the  cap  so 
that  it  barely  touches  the  charge,  and  the  cap  not  too 
tightly  crimped  on.  If  the  fuses  are  to  be  used  in  damp 
or  wet  places,  a  further  precaution  should  be  taken  by 
using  P.  &  B.  paint,  heavy  grease,  or  some  other  mate- 
rial which  is  water-tight,  to  keep  all  moisture  from 
penetrating  the  cap  through  the  junction  between  the 
cap  and  fuse.  Whenever  a  sufficient  quantity  of  fuses 
are  capped  and  ready  for  use,  they  are  put  into  special 
fuse  cans.  These  may  be  made  by  taking  carbide  cans, 
cutting  them  down  about  9  in.,  fitting  them  with  special 
lids  which  are  water-proof,  and  lining  the  inside  with 
felt  \  in.  thick.  The  lids  should  be  lined  as  well  as 
the  cans.  The  fuses  are  coiled  and  placed  inside  these 
cans  and  transported  in  this  manner  to  the  shafts,  from 
which  they  are  transferred  to  the  different  underground 
fuse  houses.  The  fuse  cans  should  be  sent  back  to  the 


EXPLOSIVES 


53 


fuse  house  on  surface  to  be  refilled  as  the  supply  under- 
ground runs  low. 

From  the  standpoint  of  efficiency,  the  capping  of  fuses 
by  men  specially  employed  for  that  purpose  has  proved 
to  be  a  success  at  a  number  of  mines.  In  one  instance, 
two  men  do  all  the  cutting  and  capping  on  the  surface 
for  the  entire  mine,  averaging  3000  caps  a  day.  This 


K  Spoo/s      //-= 

of  Fuses  /'/— = 

here    A//=L_== 


FIG.  3.    ADJUSTABLE  FUSE  CUTTER 

work  was  formerly  part  of  the  duties  of  sixteen  powder 
men,  who  cut  and  capped  fuse  for  their  individual 
levels,  and  who  are  now  required  to  do  repair  work  and 
cleaning  tracks  in  the  time  formerly  spent  in  crimping 
caps.  At  another  mine,  one  man  is  employed  in  a  well- 
ventilated  fuse  house  underground,  and  cuts  and  caps 
from  1100  to  1400  fuses  a  day. 

STEMMING  OR  TAMPING 

Stemming,  or  tamping,  as  it  is  called,  is  extensively 
used  in  practically  all  mines  except  metal  mines.  Its 
use  has  been  in  practice  in  coal  and  iron  mines  and  in 
mines  in  England  and  on  the  Continent  for  many  years, 


54 


STANDARDIZATION  OF  MINING  METHODS 


but  it  is  not  extensively  used  in  the  metal  mines  in 
this  country.  In  Michigan,  where  many  of  the  miners 
originally  came  from  England,  stemming  is  used,  for 
the  reason  that  the  men  have  been  trained  in  that 
country  to  the  idea  that  stemming  goes  with  the 
powder,  but  its  use  has  never  been  enforced  by  the 


FIG.  4.    FUSE  CANS 

operators  in  the  West;  and  the  miner  has  come  to 
know  that  by  filling  the  hole  with  powder  and  using 
the  explosive  instead  of  stemming  he  can  satisfactorily 
pull  the  ground,  and,  inasmuch  as  the  company  fur- 


EXPLOSIVES 


55 


nished  the  powder,  there   is  no  need  for  him  to  be 
economical. 

It  naturally  became  the  practice  for  miners  in  this 
country  to  load  a  hole  with  powder  and  then  use  an 
extra  amount  for  stemming,  thus  establishing  a  custom 
for  the  use  of  an  excessive  amount.  In  this  connection 


FIG.  5.    MAKING  STEMMING  AT  A  MEXICAN  MINE 

it  may  be  noted  that  contractors  in  the  Southwest  who 
furnish  their  own  powder  generally  use  stemming.  The 
miners  working  on  day's  pay,  on  the  other  hand,  never 
do  so,  as  they  well  know  that  holes  loaded  with  an 
excessive  amount  of  powder  without  stemming  will 
satisfactorily  break  the  ground,  and  that  the  use  of 
stemming  entails  extra  work  and  is  contrary  to  custom. 
In  justification  of  the  miners'  attitude  it  should  be  taken 
into  account  that  not  enough  has  been  done  in  eliminat- 
ing missed  holes,  as  it  is  dangerous  to  clear  out  the 
stemming  in  a  missed  hole  in  order  to  blast  it  over 
again.  It  is  therefore  absolutely  essential  that  the 
number  of  missed  holes  be  reduced  to  a  minimum  before 
making  the  use  of  stemming  compulsory. 

STEMMING  INCREASES  EFFICIENCY 
It   is   an   established   fact  that   stemming   increases 


56  STANDARDIZATION  OF  MINING  METHODS 

the  efficiency  of  the  charge,  and  Technical  Paper  No. 
17  ("The  Effect  of  Stemming  on  the  Efficiency  of 
Explosives")  of  the  U.  S.  Bureau  of  Mines,  describes 
experiments  showing  that  the  gain  in  work  accom- 
plished when  dynamite  is  'tamped  varies  from  about 
35%  with  the  quick-acting  to  over  90%  with  the  slow- 
acting  explosives.  De  Kalb  says  that  in  no  case  is 
detonation  absolutely  perfect  under  ordinary  conditions, 
but  this  perfection  is  approached  more  closely  according 
to  the  concentration  of  the  explosive  impulse,  due  to 
good  confinement. 

Experiments  made  by  the  Western  Australian  Gov- 
ernment Commission,  and  described  in  the  "Blue  Book" 
of  1905,  showed  that  the  tamping  of  charges  has  a 
marked  effect  on  the  proper  detonation  of  the  explosive 
used.  When  bore  holes  are  tamped  carelessly,  or  when 
no  tamping  is  used,  the  lack  of  confinement  apparently 
causes  a  small  part  of  the  explosive  to  be  detonated 
incompletely,  and  consequently  more  offensive  fumes 
are  given  off  than  when  the  charge  is  tamped  properly. 

Some  of  the  arguments  advanced  against  the  use  of 
stemming  are  as  follows: 

1.  It  takes  longer  to  load  a  round  of  holes  when  stem- 
ming   is    used. 

2.  In  the  case  of  missed  holes,  the  stemming  must 
either  be  cleaned  out  or  another  hole  drilled  alongside; 
and  if  the  miner  is  careless  there  is  danger  of  drilling 
into  the  unexploded  charge. 

3.  It  is  contrary  to  custom,  especially  in  the  Western 
States. 

The  advantages  of  stemming  are: 

1.  Greater  efficiency  of  the  explosive. 

2.  .Complete  detonation,  and,  therefore,  a  minimum 
amount  of  noxious  gases. 

3.  A  saving  in  powder  and,  incidentally,  in  cost. 

CLASSES  OF  STEMMING  USED 

Different  kinds  of  stemming  are  used  on  a  small 
scale  in  some  of  the  metal  mines  in  the  West.  In 


EXPLOSIVES  67 

one  mine,  for  example,  the  powder  man  collects  several 
boxes  of  clay,  which  he  brings  to  the  powder  magazine. 
The  clay  is  rolled  into  balls  about  the  size  of  the  or- 
dinary baseball,  and  he  hands  these  to  the  miners  when 
they  come  for  the  powder.  About  half  this  stemming  is 
scattered  along  the  way  to  the  working  places.  When 
ready  to  load,  the  miner  is  often  so  rushed  for  time 
that  he  is  unable  to  take  these  large  balls  of  clay  and 
roll  them  down  by  hand  to  fit  the  holes,  so  the  remainder 
of  the  stemming  is  usually  lost.  In  cases  where  the 
miners  actually  do  use  it,  the  quantity  is  so  small  that 
the  effect  is  negligible. 

Another  method  which  is  being  tried  in  some  places 
is  the  use  of  paper  forms  made  the  same  size  as  the 
powder.  These  forms  are  filled  in  some  instances  with 
wet  and  in  others  with  dry  sand  (see  Fig.  5).  So 
far,  this  has  been  tried  out  only  occasionally  in  certain 
mines,  and  therefore  has  not  produced  the  results  for 
which  it  was  intended.  Mill  tailings  are  sometimes 
used,  the  fine  dust  in  drill  holes  has  been  collected  and 
used  in  others,  and  dust  from  the  ores  has  been  tried 
in  a  few  mines,  but  this  has  not  as  yet  passed  beyond 
the  experimental  stage. 

VALUE  OP  CLAY  FOR  STEMMING 

It  has  been  proved  by  experiments  that  plastic  clay 
which  has  been  properly  tempered  is  most  suitable  for 
stemming.  Consequently,  when  an  attempt  is  made  to 
introduce  the  practice  in  a  mine,  it  is  advisable  to  use 
the  best  material  available.  At  the  property  of  the 
Mogollon  Mines  Co.  a  machine  was  devised  and  has 
been  in  use  for  some  time  to  mold  clay  in  the  desired 
form,  and  a  system  also  has  been  adopted  by  which 
the  stemming  is  properly  distributed. 

In  the  larger  mines  3000  or  more  shots  are  fired 
every  day.  This  requires  a  large  amount  of  stemming 
and  necessitates  manufacture  on  a  large  scale.  After 
a  careful  study  of  this  matter  and  after  taking  up  the 
question  with  authorities  on  brick-making  at  different 


58  STANDARDIZATION  OF  MINING  METHODS 

plants,  I  came  to  the  conclusion  that  a  brick-and-tile 
machine,  with  a  die  made  to  suit  the  measurements  of 
stemming,  would  be  practical  for  such  a  purpose.  Fig. 
6  shows  a  machine  of  this  kind,  capable  of  turning  out 
stemming  in  quantity  greater  than  required  at  the  aver- 
age mine.  For  this  reason  a  smaller  machine  should 
be  designed  to  meet  requirements. 

USE  OF  AMERICAN  AUGER  MACHINE 

The  clay  from  which  the  stemming  is  to  be  made 
should  first  be  thoroughly  mixed  and  tempered  in  a  pug 
mill,  boulders  broken  and  sufficient  water  added  to  make 
it  plastic.  After  being  thoroughly  mixed,  the  clay  is 
run  through  the  stemming  machine  and  forced  out 
through  a  cluster  die,  containing  six  to  ten  orifices 
each  approximately  one  inch  in  diameter,  cut  into  about 
ten-inch  lengths,  and  wrapped  in  paper.  This  paper 
should  be  of  different  color  to  that  used  for  the 
powder.  The  product  should  be  sent  to  the  various 
shafts,  lowered,  and  taken  to  the  powder  magazines 


FIG.  6.    AMERICAN  AUGER  MACHINE  FOR  MAKING  STEMMING 

together  with  the  powder.  When  the  miner  goes  for 
his  powder  and  caps  he  should  receive  the  stemming  at 
the  same  time. 

A  plant  such  as  is  suggested  could  be  designed  and 
constructed  at  a  reasonable  cost.  The  pug  mill  and 
stemming  machine  can  be  operated  by  electricity  at 
small  expense,  and  the  clay  obtained  from  waste  dumps, 


EXPLOSIVES  69 

and  the  quantity  of  water  used  would  be  negligible. 
When  it  is  considered  that  the  machine  shown  in  the 
illustration  is  capable  of  turning  out  from  1000  to 
2000  building  bricks  per  hour,  it  is  obvious  that  with 
a  smaller  machine,  designed  to  meet  the  requirements 
of  the  average  mine,  two  men  could  turn  out  sufficient 
stemming  within  a  few  hours  to  supply  the  daily  needs, 
and  for  the  remainder  of  the  shift  they  could  be  put 
to  other  work. 

LOADING  AND  BLASTING  PRACTICE 

Great  care  should  be  exercised  in  slitting  the  powder 
and  putting  it  in  the  holes.  Except  in  the  case  of  very 
wet  holes,  every  stick  of  powder  should  be  slit.  A 
wooden  tamping  stick  should  be  used,  and  the  powder 
carefully  tamped  so  that  it  will  fill  all  the  air  spaces 
in  the  drill  holes. 

In  placing  the  primer,  there  is  considerable  difference 
of  opinion  as  to  where  it  will  have  the  greatest  effect. 
It  is  best  to  decide  on  one  particular  place,  let  that 
be  the  common  practice,  and  adopt  it  as  standard. 
Though  it  is  possible,  with  the  uninflammable  ammonia 
dynamite  and  the  gelatins  so  extensively  used  in  mining, 
to  place  the  primer  anywhere  with  small  danger  of  igni- 
tion, (providing  a  high  quality  of  fuse  is  used),  the 
tamping  can  be  done  more  effectively  if  the  primer  is 
placed  near  the  top  of  the  charge.  On  the  other  hand, 
the  explosive  is  more  generally  detonated  by  having 
the  cap  in  the  center  of  the  charge.  In  the  Southwest, 
the  general  practice  seems  to  be  to  place  the  primer 
near  the  bottom  of  the  hole;  and  although  there  is  a 
possibility  of  the  powder  being  set  on  fire  by  the  fuse 
before  it  reaches  the  detonator,  the  use  of  the  best 
quality  of  fuse  seems  to  have,  so  far,  avoided  this 
danger. 

In  making  up  the  primer  many  methods  have  been 
practiced,  of  which  Fig.  7  shows  one  of  the  most  popu- 
lar. In  the  practice  illustrated  misfires  are  of  frequent 
occurrence.  In  those  instances  where  the  fuse  was  cold 


60  STANDARDIZATION  OF  MINING  METHODS 

it  was  doubled  up  by  the  miner  so  as  to  break,  which 
was  also  the  cause  of  misfires.  The  wrong  way  and 
the  right  way,  shown  in  Figs.  7  and  8,  respectively, 
should  be  illustrated  by  blueprints,  which  should  be 
placed  in  front  of  the  mine  office  for  the  benefit  of 
the  men.  Orders  should  also  be  given  to  the  men  re- 
garding the  standard  practice  which  has  been  adopted. 

After  loading  and  placing  the  primer  (in  case 
stemming  has  been  introduced  and  become  a  regular 
practice),  the  remainder  of  the  hole,  to  within  about 
six  inches  of  the  collar,  should  now  be  filled  with  stem- 
ming. By  leaving  this  distance  unfilled  it  will  then  be 
possible,  in  the  case  of  a  misfire,  to  ascertain  the  exact 
direction  of  the  missed  hole,  so  that  another  may  be 
drilled  with  safety. 

The  fuses  are  now  spit  about  i  in.  so  that  they 
can  easily  be  ignited.  The  old  method  of  using  a 
piece  of  fuse  about  a  foot  long  and  cutting  it  about 
every  inch  is  the  most  practical  fuse  spitter  in  use 
at  present.  At  this  moment  caution  should  be  exercised 
to  spit  the  cut  holes  first,  as  many  rounds  are  lost 
on  account  of  miners  neglecting  this  important  point, 
and  hastily  spitting  the  fuses,  regardless  of  the  order 
in  which  they  should  be  fired. 

DANGER  FROM  MISSED  HOLES 

As  previously  mentioned,  before  stemming  is  used, 
the  number  of  missed  holes  must  be  reduced  to  a  mini- 
mum. The  causes  have  frequently  been  enumerated  and 
are  well  known.  A  thorough  investigation  of  conditions 
should  be  made  at  mines  where  a  large  percentage  of 
missed  holes  occur,  and  the  causes  eliminated.  Fre- 
quently, the  use  of  a  stronger  detonator  will  have  a 
marked  effect  on  the  reduction  of  missed  holes.  If, 
therefore,  proper  attention  is  given  to  the  handling  and 
care  of  powder,  caps,  and  fuse,  as  outlined  above,  and 
only  the  best  quality  is  used,  there  should  be  few 
misfires.  In  some  mines  the  number  has  already  been 
reduced  to  less  than  1%,  and  at  one  in  particular,  where 
a  strong  detonator  is  used,  the  monthly  average  is  about 


EXPLOSIVES 


61 


0.25%.  In  headings  where  a  great  deal  of  water  is 
encountered,  or  when  sinking  in  wet  ground,  it  is  gen- 
erally advisable  to  blast  by  electricity  in  order  to  elimi- 
nate missed  holes. 


V 


FIG.7  FIG.6 

WRONG  AND  RIGHT  WAYS  OF  MAKING  UP  THE  PRIMER 

GASES  FROM  EXPLOSIVES 

Some  conception  may  be  formed  of  the  effects  of  gases 
produced  by  explosives  from  the  fact  that,  in  one  mine, 
37  men  were  gassed  during  a  year,  of  whom  11 
(29.72%)  were  gassed  in  stopes,  12  (32.43%)  in  drifts, 
12  (32.43%)  in  raises,  and  2  (5.42%)  in  winzes.  The 
total  time  lost  was  84i  shifts,  with  individual  losses 
up  to  10  shifts  per  man.  At  another  mine  21  men  were 
gassed  in  a  single  night  as  the  result  of  excessive  powder 
smoke  and  gas  from  blasting. 

When  it  is  considered  that  one  stick  of  H-in.  40% 
gelatin  dynamite  will  produce  approximately  1.54  cu.ft. 
of  carbon  dioxide  and  0.09  cu.ft.  of  carbon  monoxide 
(calculated  for  atmospheric  pressure  at  sea  level),  and 


62  STANDARDIZATION  OF  MINING  METHODS 

that  in  a  drift  or  raise  averaging  10  to  20  holes,  with 
six  sticks  of  powder  to  a  hole,  there  would  be  about 
90  times  this  amount,  or  157  cu.ft.  of  gas,  some  idea 
can  be  formed  of  the  effect.  It  takes  approximately 
650  cu.ft.  of  fresh  air  to  dilute  the  gas  from  one  stick 
of  such  powder  and  improve  the  atmosphere  until  the 
carbon  dioxide  present  is  0.25%.  For  the  drift  men- 
tioned, a  relatively  larger  amount,  about  58,500  cu.ft., 
of  good  air  would  be  necessary. 

Stopes  worked  by  undercutting  systems,  where 
boulders  must  be  plugged  during  the  shift;  caving 
systems  where  ore  is  simply  drawn  off  and  where  it 
is  necessary  to  put  in  more  holes  with  the  stoper  from 
the  chute  in  order  to  cave  the  ground  above;  horizontal 
or  incline  cut-and-fill  stopes,  necessitating  the  breaking 
of  boulders  for  the  chutes;  top  slices,  in  order  to  break 
the  ore  in  case  the  previous  shift  did  not  blast — all 
require  blasting  to  be  done  during  the  shift.  This 
results  in  an  excess  of  gas  over  and  above  that  formed 
from  the  regular  blasting  at  the  end  of  the  shift.  The 
greater  the  atmosphere  is  vitiated,  the  more  good  air 
must  be  produced.  This  requires  more  power  and  closer 
supervision  of  the  ventilating  system  in  order  to  have 
the  place  ventilated  as  thoroughly  as  possible;  and  this 
naturally  adds  to  general  cost. 

The  large  amount  of  gas  produced  is  due  partly  to 
the  excessive  use  of  powder  on  the  part  of  the  miners 
and  partly  to  incomplete  detonation.  The  former 
naturally  multiplies  the  volume  of  gas,  and  it  is  a  well- 
known  fact  that  when  a  charge  of  dynamite  burns 
instead  of  exploding,  a  much  greater  amount  of  carbon 
monoxide  is  formed,  and  other  harmful  gases  are  pro- 
duced. Incomplete  detonation,  due  to  the  use  of  caps 
of  insufficient  strength,  or  the  presence  of  moisture  in 
the  cap,  adds  to  the  seriousness  of  the  situation  by 
increasing  the  percentage  of  dangerous  gases  present. 
The  efficiency  of  the  explosive  is  also  reduced  when 
the  charge  burns  instead  of  exploding;  in  fact  some 
authorities  estimate  its  efficiency  to  be  only  about  50%. 


EXPLOSIVES  63 

"In  practice,  the  fact  that  an  explosive  has  not  been 
properly  detonated  is  made  manifest  principally  by 
the  production  of  considerable  quantities  of  disagree- 
able and  poisonous  fumes,  the  presence  of  unexploded 
powder,  the  small  amount  of  work  done  by  the  powder, 
and  often,  with  high  explosives,  a  section  of  the  bore- 
hole in  which  the  powder  has  burned  is  unaffected. 
.  .  .  The  bad  fumes  in  incompletely  detonated  pow- 
der are  due  to  the  fact  that  its  decomposition  was 
effected  at  a  temperature  below  that  which  corresponds 
to  the  most  violent  chemical  action.  The  result  is  that 
instead  of  producing  nitrogen  and  carbon  dioxide  in  the 
gases  from  the  explosion,  both  the  poisonous  nitric  oxide 
and  carbon  monoxide  are  formed.  .  .  .  The  weaker 
effect  from  imperfectly  detonated  powder  is  due  largely 
to  two  causes — lesser  heat  of  formation  of  carbonic 
oxide  gas  and  the  heat  absorbed  in  the  formation  of 
nitric  oxide.  Thus,  when  carbon  monoxide  and  nitric 
oxide  are  present  in  the  gases  from  an  explosion,  poorer 
results  are  obtained  than  when  carbon  dioxide  and 
nitrogen  are  liberated.  Further  investigation  during 
late  years  has  shown  the  presence  of  volatilized  nitro- 
glycerin  in  the  fumes  from  burning  or  incompletely 
detonated  dynamite.  Nitroglycerin  is  very  volatile,  and 
a  small  quantity  may  easily  be  evaporated  by  the  heat 
from  burning  powder.  This  is  made  manifest  by  the 
action  of  these  fumes  on  human  beings.  It  is  a  com- 
mon fact  that  men  breathing  the  fumes  from  nitro- 
glycerin  explosives,  particularly  when  improperly 
detonated,  get  violent  headaches,  similar  to  those  due 
to  slight  nitroglycerin  poisoning.  This  great  simi- 
larity, and  the  fact  that  the  same  treatment  effects  a 
cure  in  both  cases,  are  accepted  by  a  number  of  author- 
ities as  satisfactory  evidence  that  nitroglycerin  vapor 
is  present  in  the  fumes  from  poorly  detonated  or 
burning  dynamite." 

FORMULATING  OF  BLASTING  RULES  DIFFICULT 
Though  it  is  difficult  to  formulate  rules  regarding 


64  STANDARDIZATION  OF  MINING  METHODS 

blasting  in  mines  where  the  method  employed  neces- 
sitates the  use  of  explosives  during  shifts,  something 
can  still  be  done  to  systematize  the  work  as  much  as 
possible.  If  men  are  working  over  a  grizzly  and  find 
it  necessary  to  blast  frequently,  then  instead  of  blast- 
ing each  boulder  separately  as  they  come  to  it,  they 
may  be  able  to  keep  the  ore  running  until  they  have 
five  or  six  of  these  boulders  together.  In  place  of 
the  customary  one,  two,  or  three  sticks  of  powder 
on  each  boulder,  they  should  put  a  small  hole  in 
each  with  a  Jackhamer,  insert  about  half  a  stick  of 
powder,  a  strong  detonator,  and  a  little  stemming  on 
the  top.  This  will  generally  break  the  rock  just  as 
effectively  and  reduce  the  total  quantity  of  powder  from 
10  or  12  sticks  to  about  2i  or  3.  This  would  result 
in  a  marked  effect  on  the  ventilation  in  general,  as  it 
would  decrease  the  quantity  of  poisonous  or  noxious 
gases  which  are  generated  in  the  first  place,  and  thereby 
require  less  air  to  dilute  the  products  of  combustion. 
It  would  also  effect  a  considerable  saving  in  powder. 
The  organization  can  insist  on  these  different  opera- 
tions until  they  become  habitual  with  the  men  and  finally 
become  standard. 


Section  V 

Fire  Protection 
of  Metal  Mines 


•  ^IRES  are  the  greatest  hazards  encountered  in  the 
•H  development  and  operation  of  mines.  The  loss  of 
JL  life,  damage  to  property,  and  utter  disorganization 
of  regular  routine  which  frequently  accompany  them 
make  them  occurrences  to  be  dreaded  by  mining  organ- 
izations. The  period  of  confusion  immediately  follow- 
ing their  discovery  and  preceding  the  time  when  an  or- 
ganized method  of  attack  shall  have  been  planned  is 
generally  the  most  critical,  due  to  the  lack  of  definite 
working  plans;  men  frequently  expose  themselves  un- 
necessarily and  often  incur  serious  injuries,  which  at 
times  prove  fatal. 

During  recent  years  there  have  been  approx- 
imately 35  active  mine  fires  in  the  Southwest.  Twelve 
of  these  were  shaft  fires,  but  the  majority  occurred  in 
stopes,  or  in  drifts  and  raises  directly  connected  with 
stopes. 

CAUSES  OF  MINE  FIRES  VARIED 

Fires  result  from  many  causes,  among  which  are  de- 
fective electric  wiring,  use  of  candles,  spontaneous  com- 
Jbustipn  in  pyritic  orebodies,  and,  I  regret  to  say,  in- 


66  STANDARDIZATION  OF  MINING  METHODS 

cendiarism.  In  this  connection  it  might  be  stated  that 
40%  of  the  fires  mentioned  above  were  due  to  this  lat- 
ter cause. 

Fires  in  surface  buildings  were  formerly  the  cause 
of  many  disasters  underground.  The  fire  was  commu- 
nicated from  the  building  to  the  shaft  and  thence  to 
the  mine  workings.  In  recent  years,  however,  steel 
headframes  and  other  fireproof  construction  have  come 
into  general  use,  and  timber  connections  between  build- 
ings and  shaft  collars  have  been  avoided.  A  conven- 
ient water  supply  is  always  available,  and  the  possibil- 
ity of  a  mine  fire  from  this  source  has  practically  been 
eliminated. 

Friction,  due  to  moving  ground,  intensified  by  caves 
and  extreme  pressure,  is  often  the  cause  of  fire  in  ores 
containing  considerable  pyrite,  chalcocite  or  chalcopyrite, 
and  recently  it  was  demonstrated  that  a  fire  can  exist 
in  sulphide  ores  the  sulphur  content  of  which  is  ap- 
proximately 3%.  Fires  in  metal  mines  have  become 
so  frequent  that  almost  every  district  has  its  history 
of  them,  and  most  companies  are  now  taking  precautions 
to  meet  such  emergencies  when  they  arise. 

Various  methods  of  fighting  fires  have  been  employed 
at  the  different  mines  with  more  or  less  success.  The 
plan  most  generally  resorted  to  in  the  past  has  been  that 
of  sealing  up  the  fire  or  fire  district,  and  allowing  it  to 
remain  for  a  considerable  length  of  time,  extending  in 
some  cases  over  a  period  of  years,  while  this  portion  of 
the  workings  was  temporarily  abandoned.  This  has 
proved  fairly  successful  in  mines  containing  large  areas 
of  low-grade  ore,  but  where  the  mine  is  a  high-grade 
producer,  the  removal  of  a  large  portion  of  the  orebody 
from  active  stoping,  even  if  only  temporarily,  would  se- 
riously curtail  production. 

At  one  mine,  a  complete  mine-fan  equipment  has  been 
installed  on  the  lowest  level,  which  may  be  started  in 
case  of  fire  by  entering  the  workings  through  an  ad- 
joining mine.  This,  in  addition  to  a  fire-fighting  equip- 
ment, consisting  of  portable  blowers,  ventilating  pipe, 


FIRE  PROTECTION  OF  METAL  MINES  67 

bratticing,  helmets,  etc.,  together  with  a  set  of  rules 
prescribing  duties  for  the  organization,  makes  up  the 
fire-protection  system. 

Another  company  places  entire  reliance  on  teams  of 
trained  helmet  men.  It  is  expected  that  these  will  be 
able  to  cope  successfully  with  any  emergency  which 
may  arise. 

A  third  mine  has  a  system  of  bulkheading  and  patrol 
in  force.  Bulkheads  are  put  in  as  seals  at  all  stopes 
which  are  not  in  operation.  Though  the  seals  are  not 
airtight,  they  could  easily  be  made  so  in  case  of  fire. 
The  patrol  has  the  specific  duty  of  visiting  every  work- 
ing place  shortly  after  the  men  go  off  shift.  Gates 
are  put  in  at  tunnel  entrances  to  the  mines  and  are 
kept  locked  both  day  and  night.  When  the  shift  is  go- 
ing on,  a  watchman  opens  the  gates  and  checks  the  men, 
allowing  only  those  who  have  time  cards  to  enter.  When 
the  shift  goes  off,  the  watchman  again  takes  charge.  If 
motors  are  to  take  timber  and  other  supplies  into  the 
mine  through  the  gates  during  the  shift,  it  is  necessary 
for  the  motorman  to  have  a  key  to  the  gates  in  order 
to  pass  through.  Screen  gates,  such  as  shown  in  Fig. 
1,  are  also  put  in  front  of  important  shafts,  so  that 
it  is  impossible  for  any  one  to  get  near  these  shafts  ex- 
cept when  the  foremen  and  bosses  go  through,  or  when 
the  shift  is  coming  on  or  going  off.  In  the  district  in 
which  this  mine  is  situated  there  have  been  a  number 
of  incendiary  fires  which  have  necessitated  these  ex- 
treme measures. 

EACH  MAN'S  DUTY  SPECIFIED  IN  CASE  OF  FIRE 

At  a  fourth  mine  a  set  of  rules  is  in  force  which 
governs  the  actions  of  practically  every  man  employed, 
from  the  one  who  discovers  the  fire  right  up  through 
the  organization  to  the  operating  department.  For 
example:  A  miner  discovers  fire.  He  reports  to  the 
cagers,  who  in  turn  report  to  the  hoisting  engineer.  The 
hoisting  engineer  telephones  central  and  also  the  power 
plant,  which  flashes  a  general  alarm  and  shuts 


68  STANDARDIZATION  OF  MINING  METHODS 

off  the  mechanical  ventilation.  Central  notifies  the  elec- 
trical, mechanical,  safety,  supply,  and  operating  depart- 
ments. Having  notified  the  hoisting  engineer,  the 
cagers  proceed  to  close  all  fire  doors  and  turn  water  into 
the  compressed-air  lines  while  on  surface.  They  then 
visit  the  different  levels  to  see  that  the  doors  are  shut, 
while  the  men  who  have  received  the  alarm  are  coming 
to  the  shaft  stations,  there  to  be  checked  off  by  the  shift 
boss.  By  this  time,  the  men  of  the  operating  department 
arrive  and  take  charge  of  the  situation.  Aside  from 
these  definite  instructions  to  individuals,  there  is  a 
complete  supply  of  fire-fighting  equipment  always  on 
hand  in  the  mechanical  department,  and  oxygen  helmets 
and  pulmotor  are  kept  in  stock,  ready  to  be  transported 
immediately. 

At  another  large  mine,  signals  are  given  on  the  lights, 
calling  the  men  to  the  shaft  stations,  there  to  await 
orders.  Refuge  chambers  are  provided  by  means  of 
drifts  in  dead  ends  on  certain  levels,  where  men  may 
enter,  close  the  door  and  turn  on  the  compressed  air  and 
thus  remain  until  the  rescue  party  calls  for  them,  if  they 
are  unable  to  leave  the  mine. 

At  practically  all  mines  there  are  hoses  and  connec- 
tions at  the  collar  of  the  shaft  so  that  a  stream  of  water 
may  be  turned  into  the  shaft  in  a  short  time.  In 
some  places  a  water  line  is  run  around  the  collar  of  the 
shaft  so  as  to  distribute  the  water  properly.  There  is 
a  possibility,  in  case  of  a  fire,  of  the  water  not  reach- 
ing it  immediately  by  this  method. 

METHODS  USED  QUESTIONABLE  IN  SOME  WAYS 

Some  of  the  features  of  these  fire-protection  systems 
which  are  in  use  at  the  present  time  are  com- 
mendable, while  others  are  open  to  criticism.  Merely 
turning  a  water  line  into  the  collar  may  not  necessarily 
extinguish  a  shaft  fire,  as  the  water  may  not  come  in 
direct  contact  with  that  part  of  the  shaft  which  is 
burning.  On  the  other  hand,  a  series  of  sprays  placed 
at  regular  intervals  in  the  shaft  distributes  the  water 


FIRE  PROTECTION  OF  METAL  MINES  69 

in  such  a  manner  that  every  portion  of  the  shaft  becomes 
soaked  in  a  few  minutes. 

Automatic  sprinklers,  which  have  been  used  to  much 
advantage  in  buildings,  are  not  suitable  for  use  in 
shafts.  These  sprinklers  operate  when  the  heat  of  the 
fire  becomes  great  enough  to  melt  a  plug,  the  removal 
of  which  allows  the  water  to  flow.  They  are  extremely 
dangerous  in  shafts  where  there  are  no  fire  doors,  for 
if  a  fire  breaks  out  in  the  shaft,  all  the  sprays  begin 
to  operate  at  a  certain  temperature  and  are  not  subject 
to  control.  This  changes  the  draft  and  forces  the  smoke 
and  gas  into  the  workings,  thereby  endangering  all  the 
men  in  the  mine.  Consequently,  if  sprays  of  this  char- 
acter are  to  be  used,  they  should  be  controlled  'by  a  valve 
on  the  surface  and  should  be  connected  to  a  separate 
water  line  installed  for  this  purpose. 

Refuge  chambers  have  been  used  to  advantage  in  coal 
mines  in  case  of  explosion,  but  their  value  in  metal 
mines  is  questionable,  as  the  men  have  to  depend  on 
the  compressed  air  which  is  piped  into  the  chamber. 
Should  a  small  cave  occur  near  or  over  the  compressed- 
air  line,  the  pipe  may  be  damaged  and  the  supply  of  air 
cut  off.  In  fact,  it  becomes  necessary  at  times  to  turn 
water  into  the  compressed-air  line  in  order  to  put 
water  on  the  fire,  which,  of  course,  necessitates  turning 
off  the  compressed  air  entirely. 

Chemical  engines  have  been  suggested  for  employ- 
ment at  mine  fires.  However,  their  use  is  accompanied 
by  serious  danger,  which  is  apparent  when  one  considers 
the  large  volume  of  gas — at  least  100  cu.ft. — which  is 
released  with  one  charge.  On  the  surface  this  would  be 
diluted  without  danger  to  any  one,  but  underground, 
it  is  merely  another  menace  added  to  that  of  the  gas 
produced  by  the  fire. 

HELMET  WORK  REQUIRES  CAREFUL  PLANNING 

Though  helmet  men  are  relied  upon  entirely  at  some 
camps,  their  work  should  always  be  mapped  out 
with  great  caution.  They  should  be  sent  into  smoke 


70  STANDARDIZATION  OF  MINING  METHODS 

or  gas  but  a  short  distance.  Only  a  limited  amount 
of  work  can  be  expected  of  them,  as  a  man  wearing  an 
oxygen  helmet  does  only  about  20%  of  the  amount  of 
work  that  he  would  do  when  working  in  good  air  with- 
out the  apparatus. 

Various  forms  of  fire  alarms  have  been  suggested, 
such  as  turning  off  the  compressed  air,  flashing  an 
alarm  over  the  electric  wires,  etc.  The  disadvantages  of 
these  are  that  the  compressed  air  frequently  goes  off 
during  the  shift,  due  to  other  causes  such  as  minor 
troubles  at  the  power  plant,  and  that  in  many  cases 
electric  wires  do  not  extend  into  distant  workings. 

Many  working  shafts  are  now  being  fireproofed  by 
means  of  concrete  or  gunite.  This  is  most  effective  but 
quite  expensive  and  is  not  justified  where  the  life  of  the 
shaft  is  comparatively  short. 

STANDARD  METHOD  OUTLINED  FOR  PROTECTING  SHAFT 
AND  STATIONS 

All  timbered  shafts  should  have  spraying  systems  in- 
stalled. These  act  not  only  as  a  means  of  fire  protection 
but  may  also  be  used  to  preserve  the  timber  in  dry 
shafts.  Spraying  systems  should  be  placed  in  the  shafts 
and  shaft  stations.  They  consist  of  a  main  water  line, 
extending  from  the  surface  to  the  lowest  level,  with  lines 
of  spray  on  the  dividers  between  the  shaft  compart- 
ments and  above  the  timbers  in  the  stations.  The  num- 
ber of  lines  of  sprays  will  be  determined  by  the  num- 
ber of  compartments  in  the  shaft,  a  two-compartment 
shaft  requiring  only  one  line,  and  a  three-compartment 
shaft  two  lines.  The  sprays,  of  the  lawn-sprinkler 
type,  should  be  placed  about  25  ft.  apart  in  the  shaft 
and  10  ft.  apart  in  the  stations.  Branch  water  lines, 
1  in.  in  diameter,  should  connect  the  main  line  with 
the  sprays.  Small  valves  should  be  placed  between  the 
sprays  and  the  main  water  line  to  permit  regulation  of 
the  water  at  will.  The  system  as  a  whole  should  be 
connected  with  the  main  fire-water  line  by  a  valve  on 
the  surface,  from  which  it  may  also  be  controlled. 


FIRE  PROTECTION  OF  METAL  MINES 


71 


In  case  of  fire  in  a  shaft,  should  water  be  turned  in, 
the  smoke  and  gases  are  apt  to  be  carried  into  the 
workings,  as  stated  before,  thus  endangering  the  lives 
of  the  men.  To  avoid  this  contingency,  wooden  fire 
doors  should  be  placed  a  reasonable  distance  from  the 
stations,  so  that  the  draft  can  be  controlled.  Such  doors 


FIG.  1.    TYPE  OF  SCREEN  GATE  USED  IN  FRONT  OF 
IMPORTANT  SHAFTS 

serve  to  separate  the  shaft  from  the  rest  of  the  mine 
workings  and  should  always  be  closed  in  the  event  of 
fire  in  the  shaft. 

PURPOSE  OF  FIRE  DOORS  TO  CHECK  THE  DRAFT 

Iron  fire  doors  have  been  in  use  at  many  mines  for 
a  number  of  years,  but  the  wooden  door  has  proved 
equally  satisfactory  and  much  more  economical.  The 
purpose  of  all  fire  doors  is  primarily  to  check  the  draft 
and  not  to  stop  the  progress  of  the  fire.  Should  an 


72 


STANDARDIZATION  OF  MINING  METHODS 


iron  door  be  subjected  to  intense  heat  it  would  warp 
and  the  draft  pass  through  unchecked,  thereby  exposing 
the  men  to  dangerous  gases.  Wooden  doors  should  be 


SHAFT  DOOR 


installed  far  enough  from  the  shaft  so  that  some  time 
will  elapse  before  the  fire  reaches  them. 

Fig.  2  is  a  drawing  of  a  wooden  door,  which  is  com- 
paratively air-tight.     It  is  made  of  double  1-in.  boards 


FIRE  PROTECTION  OF  METAL  MINES 


73 


with  roofing  paper  in  between,  and  is  designed  to  fit 
against  a  set  of  timber  and  not  into  a  frame.  Otherwise 
any  sag  in  the  door  or  the  frame  or  any  swelling  of 
the  wood  would  prevent  the  door  from  closing  properly. 
It  is  important  that  all  doors  should  be  hung  in  this 
fashion  and  merely  overlap  the  timbers  a  distance  of 


FIG.  2a.    DETAILS  OF  SHAFT  DOOR 

about  2  in.    A  2-in.  strip  of  canvas  should  be  nailed  on 
the  timbers  to  make  an  air-tight  joint. 

Around  the  set  on  the  sides  and  the  back  should  be 


74 


STANDARDIZATION  OF  MINING  METHODS 


built  a  concrete  stopping  8  in.  thick.  In  the  bottom  of 
the  drift  no  concrete  should  be  used,  but  it  should  be 
built  up  with  timber  to  about  2  in.  above  the  rail, 
grooves  being  cut  for  the  car  wheels  to  pass.  Standard 
iron  handles  should  be  made  and  heavy  strap  hinges 


used;  also  pulleys  with  15-lb.  weights  to  pull  and  hold 
the  door  tightly  shut  when  closed. 

An  air  control,  as  shown  in  Fig.  26,  should  accompany 
each  door.    This  is  a  simple  and  inexpensive  device  and 


FIRE  PROTECTION  OF  METAL  MINES  75 

affords  accurate  control.  A  1-in.  air  line  should  be 
put  in  each  shaft  and  connections  made  from  it  to  each 
fire  door  of  that  particular  shaft.  If  it  be  desired  to 
close  the  doors  on  each  level,  a  valve  is  shut  on  the  sur- 
face, cutting  off  the  compressed  air,  and  a  release  valve 
opened,  which  automatically  closes  all  the  doors.  These 
valves  should  be  placed  near  the  collar  of  the  shaft,  so 
that  no  time  may  be  lost  when  an  alarm  is  given. 

It  is  important  to  keep  the  automatic  closing  device  in 
good  repair,  as  otherwise,  in  the  event  of  fire,  it  would 
be  necessary  to  send  a  man  down  to  make  sure  that  all 
doors  had  shut  when  the  release  valve  was  opened.  An 
electric  control  of  the  doors  would  answer  the  same  pur- 
pose admirably,  but  would  cost  more.  Once  closed, 
either  by  air  or  electricity,  the  doors  can  be  reopened 
only  by  hand. 

Fire  extinguishers  should  be  kept  in  the  stations  for 
immediate  use  in  case  of  an  outbreak  of  fire  in  the  sta- 
tion or  adjacent  heavily  timbered  drifts. 

FIRE  RULES  SHOULD  BE  POSTED  NEAR  COLLAR 

A  set  of  rules,  similar  to  the  following,  should  be 
posted  on  the  surface  near  the  valves  which  control 
the  fire  doors  and  spraying  system,  governing  the  ac- 
tions of  the  men  and  the  steps  to  be  taken  in  case  of  a 
fire  in  the  shaft: 

First — Notify  all  men  in  the  mine  to  go  to  a  place  of 
safety  at  once. 

Second — Close  the  valve  in  the  air  line  and  open  the 
release  valve.  This  will  close  all  fire  doors. 

Third — Open  the  water  valve  connected  with  all  the 
sprays. 

Mine  telephones  should  be  installed  at  important 
points,  as  they  facilitate  getting  the  men  to  a  place  of 
safety  in  the  shortest  time,  though  it  is  better  to  get  all 
men  out  of  the  mine  in  case  of  a  shaft  fire.  The  prompt 
closing  of  the  fire  doors  will  prevent  smoke  and  gas  from 
entering  the  workings  and  allow  an  immediate  attack 
to  be  made  on  the  fire.  The  men  will  have  sufficient 


76  STANDARDIZATION  OF  MINING  METHODS 

time  to  make  their  exit  through  another  outlet  before 
the  small  amount  of  gas  which  may  leak  through  the 
doors  overtakes  them. 

FIGHTING  FIRES  IN  WORKINGS  MORE  COMPLICATED 

In  the  event  of  a  fire  in  the  mine  workings,  one  of 
the  most  serious  difficulties  is  that  of  removing  all  the 
men  before  the  workings  become  filled  with  smoke  and 
gas.  For  this  reason  it  is  necessary  to  provide  means 
of  giving  a  general  alarm,  so  that  all  men  underground 
may  be  warned  as  quickly  as  possible.  Instructions 
should  be  given  that  upon  the  discovery  of  a  fire  the 
different  sections  of  the  mine  should  be  telephoned 
and  the  alarm  spread,  and  that  the  foreman  and  shift 
bosses  be  notified  immediately.  The  men,  upon  warn- 
ing, should  go  at  once  to  the  shaft  station,  where  the 
shift  bosses  should  check  them  and  see  that  all  have 
arrived. 

As  soon  as  the  foreman  is  notified,  he  should  take 
charge  of  the  situation,  instruct  one  man  to  telephone 
the  mine  office,  have  another  put  in  the  emergency  call 
for  the  eager,  and  send  others  to  the  different  working 
places  to  make  sure  that  all  the  miners  have  been  called 
to  the  shaft  stations.  He  should  then  investigate  the 
nature  of  the  outbreak  to  decide  how  many  men  he 
will  need  to  fight  the  fire  and  how  many  should  be  sent 
to  the  surface. 

The  mine  office,  as  soon  as  informed,  should  notify 
all  departments — supply,  mechanical,  electrical,  pipe, 
safety,  and  operating  departments.  The  eager  should 
go  to  the  level  where  the  foreman  is  collecting  his  men 
and  hoist  them  as  fast  as  possible  if  it  is  found  neces- 
sary to  leave  the  mine.  His  duties  should  be  to  obey  the 
foreman.  It  should  also  be  understood  in  the  organiza- 
tion that  in  case  of  fire,  and  until  the  arrival  of  the 
superintendent,  the  mine  foreman  should  take  charge 
of  the  situation,  and,  in  his  absence,  the  assistant  mine 
foreman,  and  should  he  be  away  for  any  reason,  then 
the  senior  shift  boss.  If  it  is  found  necessary  to  leave 
the  mine,  the  men  should  follow  the  regular  routine 


FIRE  PROTECTION  OF  METAL  MINES  77 

and  report  to  their  timekeeper,  who  will  check  up  the 
shift  and  advise  the  foreman  if  any  are  missing. 

The  compressed  air  should  not  be  turned  off  and 
water  turned  in  unless  it  is  thought  advisable  by  the 
foreman  or  superintendent.  The  same  rule  should  ap- 
ply to  the  ventilation.  No  change  should  be  made  in  this 
except  in  case  of  fire  in  the  shaft.  Great  care  should 
be  exercised  in  mines  ventilated  by  mechanical  means. 
It  is  seldom  necessary  to  close  down  the  mine  fans;  in 
fact,  it  is  usually  dangerous  to  do  so,  as  the  men  are 
all  accustomed  to  the  general  direction  of  the  air  cur- 
rents, and,  if  these  are  changed,  they  are  likely  to  go 
into  dangerous  places  which  were  perfectly  safe  while 
the  fans  were  running. 

Fire-fighting  equipment  should  be  kept  on  hand  at 
all  times  and  ready  for  immediate  use.  As  soon  as  it 
arrives,  an  effort  should  be  made  to  extinguish  the 
fire  by  putting  the  fire  district  under  pressure,  build- 
ing brattices,  etc.  If  the  fire  proves  too  big  for  these 
emergency  measures,  then  a  definite  system  of  attack 
should  be  worked  out  under  the  direction  of  some  one 
experienced  in  this  line  of  work. 

EQUIPMENT  SHOULD  INCLUDE  FANS  AND  BLOWERS 

Fire-fighting  equipment  should  consist  of  one  or  more 
three-foot  disk  fans,  and  several  10-in.  blowers,  con- 
nected to  2i-hp.  motors  (fan  and  motor  mounted  on  one 
base).  These  are  necessary  for  providing  mechanical 
ventilation  in  fighting  the  fire.  All  fans  may  be  mounted 
on  trucks  so  that  they  can  easily  be  transported  to  the 
place  where  they  are  to  be  used  and  electric  connections 
made.  A  roll  of  canvas  or  roofing  paper  should  be 
kept  on  hand  for  bratticing ;  also  about  300  ft.  of  10-in. 
ventilating  pipe  for  the  blowers;  200  ft.  of  hose;  100 
sacks  of  cement  and  sand;  about  100  ft.  of  metal  lath, 
6-ft.  wide,  which  is  to  be  used  for  bulkheads  and  a 
supply  of  1-in.  boards,  10-penny  nails,  long  10-ft.  noz- 
zles, helmets,  and  a  pulmotor. 

The  storage-battery  blower  has  not  proved  successful 


78  STANDARDIZATION  OF  MINING  METHODS 

as  an  aid  to  fire  fighting.  In  the  first  place,  the  volume 
of  air  produced  by  the  small  blowers  is  of  little  conse- 
quence when  attacking  a  large  mine  fire.  The  storage 
battery  with  blower  complete  is  very  cumbersome,  es- 
pecially when  it  is  necessary  to  move  it  from  one  level 
to  another.  It  has  been  found  that  small  electric  blow- 
ers, which  can  be  transported  from  level  to  level  within 
a  few  minutes,  may  be  attached  to  the  wires  by  elec- 
tricians and  put  in  operation  in  far  less  time  than  the 
storage  battery  kind.  Moreover  they  can  be  kept  in 
operation  continuously,  whereas  the  life  of  the  storage- 
battery  blower  is  limited. 

MECHANICAL  VENTILATION  USEFUL  IN  FIRES 
The  advantages  of  mechanical  ventilation  as  a  means 
of  preventing  mine  fires  is  apparent  on  noting  that 
the  cost  of  fighting  fires  in  mines  where  it  is  em- 
ployed is  about  20%  of  that  in  mines  using  only  nat- 
ural ventilation,  as  has  been  proved  in  all  the  recent 
large  mine  fires  in  the  Southwest.  Furthermore,  in 
mines  where  mechanical  ventilation  is  used,  a  large 
number  of  smaller  fires  have  been  extinguished  before 
they  had  an  opportunity  to  develop  into  big  fires.  This 
would  have  been  practically  impossible  in  mines  where 
the  ventilation  is  not  controlled  by  mechanical  means. 
During  recent  years,  when  exploratory  work  is  to  be 
done  at  long  distances  through  smoke  and  gas,  mechan- 
ical ventilation  is  used  to  clear  the  atmosphere  as  far 
back  as  the  fire  district.  This  enables  the  helmet  crew 
to  maintain  a  station  in  the  proximity  of  the  fire,  so  that 
attacks  can  be  made  by  going  only  a  short  distance,  as, 
for  example,  50  to  75  ft.,  thus  ensuring  safety,  as  it  is 
then  possible  for  the  men  to  come  out,  even  though 
one  of  the  sets  of  apparatus  should  get  out  of  order. 
This  method  also  permits  the  largest  part  of  the  work 
around  a  mine  fire  to  be  done  by  men  without  the  oxy- 
gen apparatus,  so  that  a  far  more  rapid  attack  can  be 
made.  When  using  mechanical  ventilation  to  fight  mine 
fires,  fewer  men  have  been  knocked  out  with  smoke  and 
gas  than  in  mines  having  natural  ventilation. 


FIRE  PROTECTION  OF  METAL  MINES  79 

NATURAL  VENTILATION  GIVES  UNSTABLE  CURRENTS 

Another  consideration  of  great  importance  is  the  con- 
tinuity of  air  currents  in  a  certain  direction  when  me- 
chanically controlled,  as  contrasted  with  those  in  mines 
where  no  mechanical  system  has  been  installed,  and 
where  the  miners  are  subjected  to  the  continual  change 
of  atmospheric  conditions.  In  all  cases  of  natural  ven- 
tilation, such  changes  result  in  reversals  of  air  currents, 
depending  upon  the  season  of  the  year,  time  of  day,  etc. 

With  the  mechanical  system,  a  mine  in  which  a  fire 
exists  may  be  kept  in  continuous  operation  by  putting 
the  fire  district  under  pressure  and  thus  obviating  long 
delays,  large  expenditures  and  curtailment  of  produc- 
tion, frequently  incurred  by  the  use  of  more  expensive 
means  of  extinguishing  the  fire. 

In  case  of  fire  in  the  mine  workings,  there  should  be 
no  stopping  of  the  air  circulation,  save  in  exceptional 
cases,  when  it  is  absolutely  certain  that  all  the  men  are 
in  a  place  of  safety  and  that  the  fire-fighting  crew  will 
not  be  endangered.  It  is  the  continuous  circulation 
which  makes  possible  the  rapid  attack  on  a  mine  fire, 
and  therefore  it  should  not  be  disturbed. 

GOB  FIRES  REQUIRE  SPECIAL  HANDLING 

A  fire  in  a  gob  generally  gives  warning  before  it  ac- 
tually breaks  out.  Gases  are  given  off  which  can  be 
recognized  as  a  sign  of  incipient  or  actual  fire.  A  sus- 
pected district  should  be  patrolled  at  least  once  each 
day,  and  if  necessary,  once  each  shift.  When  it  appears 
likely  that  a  fire  may  exist  or  may  develop,  the  drifts 
and  air  courses  should  be  opened  to  a  separate  exit, 
through  which  the  smoke  and  gas  may  pass  to  the  sur- 
face. Great  care  should  be  taken  not  to  turn  water  into 
such  a  district  intermittently.  While  this  method  has 
proved  successful  in  leaching  the  heated  ores,  it  has  the 
disadvantage  of  generating  a  large  amount  of  additional 
heat,  which  may  prove  dangerous  to  the  surrounding 
district. 

In  dealing  with  such  a  problem,  large  volumes  of  air 


80  STANDARDIZATION  OF  MINING  METHODS 

should  be  used  continuously  to  cool  the  heated  district 
before  it  actually  takes  fire.  This  is  the  most  econom- 
ical way  of  lowering  the  temperature  of  a  sulphide  fire 
district.  If,  however,  the  gases  coming  from  the  dis- 
trict indicate  that  fire  actually  exists,  it  is  then  neces- 
sary to  keep  a  constant  stream  of  water  flowing  over 
the  hot  area,  while  steps  are  being  taken  to  mine  out 
this  material  and  send  it  to  the  surface.  The  waters 
naturally  become  charged  with  copper,  and  their  acidity 
frequently  damages  the  pumps  and  water  lines  as  the 
water  is  pumped  to  the  surface.  In  such  cases,  large 
quantities  of  iron  and  lime  have  been  used  to  remove 
the  copper  from  the  water  and  neutralize  the  acid. 
However,  the  returns  from  the  salvaged  copper  are  usu- 
ally far  less  than  the  damage  done  by  such  acid  waters. 

Doors  should  separate  adjoining  mines,  so  that  a  fire 
in  one  will  do  no  damage  in  another.  Old  workings 
should  be  sealed  off  with  screens  instead  of  airtight 
bulkheads.  This  will  allow  free  circulation  and  prevent 
rapid  decay  of  timber,  which  results  in  caves. 

In  general,  at  least  10  ft.  of  ore  or  waste  should  be 
kept  in  all  chutes.  In  case  of  fire  from  the  stope  above 
dropping  into  the  chute,  it  can  thus  be  checked  before 
it  burns  out  the  bottom  of  the  chute  and  caves  in  the 
entire  drift  beneath. 

Arrows,  marked  "This  Way  Out,"  should  be  placed  in 
all  important  drifts,  pointing  to  another  exit  which  is 
to  be  used  in  case  the  main  shaft  may  not  be  us^d, 
owing  to  fire.  This  presupposes  the  existence  of  cer- 
tain drifts  and  manways  which  are  to  be  kept  in  good 
repair  so  that  the  men  can  climb  to  the  surface  in 
an  emergency. 

From  time  to  time  there  should  be  conferences  be- 
tween the  mine  superintendent  and  his  foremen  and 
bosses,  at  which  the  question  of  fires  in  the  different 
parts  of  the  mine  should  be  discussed,  so  that  in  case 
of  emergency  there  will  be  no  confusion,  but  each 
foreman  and  boss  will  know  exactly  what  to  do. 


Section  VI 


Standard  Equipment 


THE  handling  of  tools  and  supplies  underground 
has  not  received  the  attention  that  the  subject  de- 
serves, although  it  is  one  of  the  important  links 
in  the  chain  of  standardized  operations  in  prospecting 
and  development.  Good  work  is  impossible  unless 
good  tools  are  provided  and  a  sufficient  supply  is 
kept  on  hand  to  meet  all  emergencies.  A  miner  was 
once  heard  to  remark:  "Give  me  the  tools,  and  I  will 
do  the  work."  This  statement  followed  the  boss's 
reprimand  at  the  end  of  a  shift  for  not  doing  a  satis- 
factory day's  work;  but  the  miner  had  been  forced  to 
spend  several  hours  seeking  an  ax  and  pick  before  set- 
ting up  to  begin  his  round.  The  fact  that  a  great 
part  of  the  miner's  time  has  to  be  spent  in  collecting 
tools  and  supplies  is  not  always  understood  by  bosses. 

When  hand  drilling  was  the  practice,  the  careful 
handling  of  the  steel  and  supplies  was  simple  compared 
to  the  complications  that  are  inseparable  from  machine 
drilling.  The  hand  miner,  on  receiving  his  hammer  and 
several  pieces  of  steel,  is  prepared  to  do  a  day's  work, 
whereas  the  machine  miner  must  assemble  a  far  greater 
variety  of  tools  and  supplies  before  he  is  ready  for  drill- 
ing. To  start  without  a  complete  outfit  means  stoppage 
of  the  work  and  a  series  of  delays  until  the  necessary 
parts  are  found. 


82  STANDARDIZATION  OF  MINING  METHODS 

DISTRIBUTION  OP  TOOLS  AND  SUPPLIES  UNDERGROUND 

A  distinct  system  for  the  distribution  of  tools  under- 
ground is  employed  in  almost  every  mine.  In  one  case 
a  number  of  locked  tool  boxes  may  be  found,  to  which 
only  the  shift  bosses  and  repair  men  have  keys.  The 
difficulty  with  this  system  is  that  the  repair  men  may 
lose  their  keys  or  the  shifters  forget  theirs,  causing 
serious  delays.  Cupboards  are  used  in  other  mines. 
These  are  always  open,  and  anybody  may  help  himself. 
As  a  general  rule,  there  are  seldom  any  tools  there,  as 
the  men  forget  to  return  what  they  take  out;  and  it  is 
hardly  possible,  with  such  a  lax  system,  to  keep  an 
accurate  check  on  the  contents  of  the  cupboards.  An- 
other plan  is  to  have  the  tool  house  and  powder  maga- 
zine in  the  same  drift,  which,  of  course,  is  extremely 
dangerous.  In  still  another  instance,  tool  houses,  with 
all  tools  and  supplies,  arranged  in  their  proper  place, 
may  be  situated  so  near  to  the  powder  magazine,  though 
in  a  separate  drift,  that  the  powderman  can  attend  to 
both.  He  checks  out  all  the  tools  at  the  beginning,  and 
receives  them  at  the  end  of  the  shift.  This  is  a  good 
system,  inasmuch  as  an  accurate  record  can  be  kept  of 
all  tools,  but  it  is  practicable  only  in  small  mines  where 
the  distances  between  the  working  faces  and  the  tool 
house  are  short.  In  large  mines,  in  which  the  workings 
are  scattered  and  the  drifts  and  raises  a  considerable 
distance  from  the  central  tool  house,  it  is  not  practicable 
to  return  the  tools  at  the  end  of  the  shift.  An  im- 
provement over  this  method  would  be  to  leave  the  tools 
in  the  different  working  places  in  the  mine,  and  have 
the  tool  "nippers"  check  them  over,  replacing  them  when 
necessary  with  others  from  the  central  tool  house. 
When  going  off  shift  the  boys  should  leave  a  report  of 
all  tools  and  supplies  taken  from  the  central  tool  house, 
and  of  the  situation  of  the  working  places  in  the  mine 
where  they  were  distributed.  A  record  should  also  be 
kept  of  all  machines  taken  from  the  working  places  and 
sent  to  the  repair  shop. 


STANDARD  EQUIPMENT  83 

CARE  OF  ROCK-DRILLING  MACHINES 

Marked  progress  has  been  made  in  drilling-machine 
design  in  the  last  few  years,  and  new  models  are  con- 
stantly put  on  the  market.  It  has,  therefore,  been  im- 
possible to  standardize  on  one  particular  machine.  In 
some  camps  it  was  considered  good  business  to  scrap 
the  old  machines  and  purchase  new  ones  at  once,  though 
other  organizations  continued  to  use  their  old  ma- 
chines and  added  new  ones  when  they  were  brought 
out.  This  led  to  an  accumulation  of  many  different 
types.  A  number  of  good  machines  are  now  available, 
and  it  is  possible  to  select  a  few  which  are  best  adapted 
to  the  kind  of  ground  that  is  being  worked,  and  to 
standardize  on  them.  At  several  properties  where 
many  different  machines  were  in  use,  a  Paynter  tester 
was  installed,  and  the  drills  were  tested  for  efficiency. 
It  was  found  that  many  machines  which  apparently 
seemed  to  be  working  well  struck  a  blow  only  one-third 
of  their  rated  strength.  Machines  in  this  condition 
involve  a  constant  loss,  and  the  tester  provided  a  rapid 
and  satisfactory  method  of  determining  how  many  drills 
among  those  which  had  been  in  stock  for  a  considerable 
time  were  fit  for  further  use.  Those  found  to  be  worn 
out  were  immediately  scrapped. 

REPAIRS  TO  ROCK  DRILLS 

A  machine  which  is  out  of  order  is  frequently  put 
aside  on  the  ground.  The  next  miner  who  comes  along 
may  not  know  of  its  condition,  and,  quite  possibly, 
may  pick  it  up  and  put  it  on  the  bar.  After  he  has 
made  his  complete  set-up  he  discovers  that  the  machine 
is  entirely  out  of  order.  Examples  of  such  a  mistake 
are  frequent,  and  time  studies  have  shown  that  in  one 
mine,  within  a  single  shift,  as  many  as  three  machines 
have  been  put  up  on  the  bar,  each  in  turn  found  to  be  in 
defective  condition. 

When  the  drill  does  not  work  well,  the  miner  under- 
ground often  opens  the  valve  chest  and  tries  to  take  the 
machine  apart.  Often  this  is  done  where  there  is  a  con- 


84  STANDARDIZATION  OF  MINING  METHODS 

siderable  amount  of  loose  dirt  and  by  a  miner  whose 
hands  are  not  clean  and  who  has  no  cotton  waste. 
Many  particles  of  dirt  and  rock  are  dropped  into  the 
mechanism,  and  by  the  time  the  miner  thinks  he  is 
through  with  the  repair  work  the  machine  is  in  a  far 
worse  condition  than  it  was  before  he  opened  it.  In  all 
cases  where  there  is  anything  seriously  wrong  with  a 
machine  it  should  be  sent  to  the  proper  repair  shop, 
which  may  be  either  underground  or  on  the  surface. 
Often,  owing  to  low  air  pressure,  the  drill  appears 
to  be  out  of  order,  and  the  machine  man  is  tempted  to 
take  it  apart  and  try  to  find  out  what  is  the  matter. 

Frequently,  the  miner  forgets  to  blow  out  the  hose 
with  compressed  air  before  connecting  the  machine,  and 
any  rock  and  dirt  accumulated  there  is  sent  directly 
into  the  machine  and  causes  much  trouble  and  delay. 
Every  miner  should  have  a  standard  oil  can  to  take  the 
place  of  the  variety  now  in  use,  which  includes  tomato 
cans,  tobacco  cans,  and  various  kinds  of  bottles.  These 
receptacles  usually  contain  dirt,  which  finds  its  way 
into  the  machine. 

SOUND  OF  MACHINE  No  INDICATION  OF  WORK  DONE 

Many  miners  believe  that,  when  a  machine  is  oper- 
ating in  a  drift,  they  can  judge  it  by  the  sound.  The  re- 
mark is  frequently  made:  "Listen  to  the  hammer  of 
that  machine.  There  is  a  good  machine.  You  can  tell 
by  the  sound  that  it  is  surely  cutting  the  rock."  In 
most  cases  judgment  made  on  such  evidence  is  based  on 
error.  The  sound  of  a  machine  is  no  indication  of  its 
actual  cutting  power.  Machines  often  sound  as  if  do- 
ing excellent  work  when,  in  reality,  operating  at  only 
50%  efficiency.  This  can  be  proved  by  the  Paynter 
testing  machine. 

Sufficient  rock  drills  should  be  kept  in  stock  under- 
ground. Accidents  will  happen  occasionally,  and  ma- 
chines get  out  of  order,  and  there  should  be  a  number 
on  hand  to  provide  against  such  an  emergency.  In 
this  event  any  man  who  starts  a  round,  even  if  he  has 


STANDARD  EQUIPMENT  85 

serious  machine  trouble,  will  be  able  to  finish  it  in  the 
shift. 

SMALL  MACHINES  OFTEN  SUITABLE 

Wherever  possible,  the  small  machines  should  be  used, 
except  in  drifting  in  extremely  hard  ground,  where  the 
larger  machine  still  holds  it  own.  Recent  competitive 
tests  have  been  made  with  several  drifting  machines 
weighing  about  150  lb.,  and  the  results  compared  with 
those  obtained  from  small  machines,  weighing  about  45 
lb.,  and  the  drilling  speed  was  found  to  be  the  same  in 
both  cases.  This  is  possible  because  the  smaller  ma- 
chine puts  in  a  smaller  hole,  and  consequently  less 
ground  is  taken  out.  The  tests  were  made  in  fairly 
hard  ground.  In  medium  ground,  however,  more  satis- 
factory results  were  obtained  with  the  small  machine 
than  with  the  larger  one ;  and  this  indicates  a  wider  field 
for  it  than  has  been  thought  possible. 

In  some  mines  the  small  machine  has  already  re- 
placed the  large  machine  in  all  development  work,  as 
well  as  in  hard  ground  in  stopes,  and  is  giving  equal  if 
not  better  satisfaction.  Moreover,  it  has  the  added  ad- 
vantage of  requiring  only  one  man,  either  to  operate 
or  set  up,  which  naturally  reduces  the  expense.  Under 
present  conditions  of  high  cost  of  production  and  scar- 
city of  competent  mine  labor  the  small  machine  should  be 
more  generally  adopted,  and  the  large  machine  and 
larger  steel  held  merely  in  reserve  for  use  in  exceptional 
and  unusual  cases. 

With  the  small  machine,  and  correspondingly  smaller- 
size  steel,  the  holes  drilled  will  naturally  be  much 
smaller  than  those  drilled  with  the  heavy  Leyner  type 
of  machine.  Consequently,  in  hard  ground,  higher- 
strength  powders  should  be  used.  This  was  formerly 
impracticable,  on  acount  of  poor  ventilation,  but  re- 
cently so  much  attention  has  been  devoted  to  an  im- 
provement in  the  methods  of  maintaining  healthful 
atmospheric  conditions,  that  it  is  now  possible  to  use 
the  higher-strength  powders  in  the  smaller  holes  with- 
out detriment  to  the  working  atmosphere. 


86  STANDARDIZATION  OF  MINING  METHODS 

HANDLING  STEEL  UNDERGROUND 

Before  it  is  possible  to  standardize  on  steel,  it  will 
be  necessary  to  standardize  on  machines.  Usually,  in 
most  mines,  four  to  six  different  kinds  of  steel  are  in 
use.  Experiments  are  being  conducted  in  one  mine  hav- 
ing an  output  capacity  of  2000  tons  a  day,  and  an  effort 
is  being  made  to  standardize  on  one  kind  of  steel  only, 
which  is  to  be  used  for  drifting  machines,  pluggers, 
and  stopers.  However,  it  has  not  been  demonstrated 
that  this  will  be  practicable;  but  it  is  reasonable  to  be- 
lieve that  the  entire  drilling  in  the  average  mine  can 
be  done  with  two  kinds  of  steel — the  large,  round,  hol- 
low steel  (li-in.  diam.)  for  large  machines  working  in 
exceptional  ground,  and  the  hollow  quarter  octagon 
(I-in.  diam.)  for  the  Jackhamer  type  and  stoping  ma- 
chines. This  is  being  done  successfully  in  several  mines, 
and  when  put  into  general  use  will  facilitate  the  stand- 
ardization of  steel  and  do  away  with  the  expense  of 
carrying  in  stock  a  number  of  different  kinds.  The 
inefficiency  resulting  and  the  confusion  caused  under- 
ground should  thus  be  materially  reduced. 

NECESSITY  FOR  UNDERGROUND  STEEL  RACKS 

Another  important  consideration  is  the  character  of 
the  steel  and  drill  bit.  A  great  deal  has  been  written  on 
this  subject,  and  much  has  been  done  to  improve  the 
design.  The  drill  bit  should  be  made  with  great  care, 
with  the  temper  which  the  ground  requires,  and  with 
the  exact  gage,  cutting  edge,  and  reaming  surfaces. 
Four  pieces  of  steel  (the  1st,  2d,  3d  and  4th)  should  be 
fastened  with  an  iron  ring  into  one  bundle,  to  facili- 
tate handling.  This  bundle  contains  all  the  steel  re- 
quired for  the  drilling  of  one  hole  to  its  proper  depth, 
and  can  be  used  over  again  until  the  steel  becomes  dulled. 

Another  problem  is  to  keep  the  steel  moving.  For 
example,  after  it  passes  through  the  drill-sharpening 
shop,  it  is  transported  to  the  shaft,  lowered  in  steel 
cars  to  the  various  stations,  and  taken  thence  to  the 
steel  racks.  Frequently,  it  is  merely  stood  up  on  the 


STANDARD  EQUIPMENT 


87 


ground,  and  becomes  plugged  before  it  is  put  in  the 
machine.  This  may  be  avoided  by  the  use  of  steel  racks, 
where  it  is  sorted  into  different  lengths  and  kinds. 
These  racks  (see  Fig.  1)  should  be  on  all  levels  under- 
ground, at  convenient  distances  from  working  places. 
The  steel  is  taken  to  the  racks  from  the  shaft  stations  on 


toe*  mask  of  Z'xIZ*  Boards,  5 'long 


FIG.  1.    UNDERGROUND  STEEL  RACK 

trucks,  and  distributed  to  the  different  tool  cars  by  the 
tool  "nippers,"  who,  in  turn,  take  the  dull  steel  back  on 
small  trucks  to  the  shaft  stations.  Here  it  is  put  into 
the  steel  cars  in  which  the  sharp  steel  has  been  brought 
down,  and  sent  to  the  surface.  A  surplus  of  sharp 
steel  should  always  be  kept  in  the  central  steel  racks,  so 
that  a  man  who  has  not  enough  steel  to  finish  his  round 
can  obtain  more. 

The  central  steel  rack  should  be  near  the  tool  house 
and  also  close  to  the  powder  magazine,  so  that  the 
powderman  who  gives  out  the  powder,  caps,  and  fuse 
can  also  attend  to  giving  out  the  tools,  supplies,  and 
steel.  He  should  also  check  all  that  comes  out,  in  order 


88 


STANDARDIZATION  OF  MINING  METHODS 


that  a  record  may  be  kept  of  the  machines  and  other 
equipment. 

STANDARD  EQUIPMENT  FOR  DRIFTING  WORK 

To  have  a  complete  outfit,  so  that  the  machine  man 
will  not  find  it  necessary  to  seek  additional  tools  or 


FIG.  2.    LEYNER  DRILL  AND  TOOL  CAR 

supplies  during  the  shift,  he  should  be  furnished  with 
standard  equipment,  consisting  of:  1  machine;  52  pieces 
of  properly  tempered  steel ;  one  50-f t.  air  hose,  and  con- 
nection; one  50-ft.  water  hose,  water  valve  and  connec- 
tion; 1  column,  arm,  clamp,  chuck  wrench,  a  monkey 


STANDARD  EQUIPMENT  89 

wrench,  and  an  18-in.  Stilson  wrench;  1  blow  pipe  and 
valve;  1  oil  can,  filled  with  proper  machine  oil;  1  ax; 
1  double  jack;  1  shovel;  1  jack  bar;  1  light  6-ft.  bar; 
1  pick;  1  scraper;  2  blocks;  6  wedges;  1  foot-block; 
gaskets,  side  rods,  nuts  and  springs;  1  powder  sack; 
1  cap  and  fuse  sack;  1  tamping  stick.  This  equipment 
should  be  sufficient  to  drill  a  standard  round,  and  the  list 
includes  everything  needed  by  the  miner  during  the 
shift,  with  the  exception  of  the  powder,  and  is  equally 
applicable  whether  large  or  small  machines  are  used. 

The  equipment  should  be  assembled  at  the  tool  house 
on  the  level  of  the  mine  on  which  the  work  is  to  be  done, 
loaded  on  the  tool  car  designed  for  that  purpose,  and 
sent  to  the  working  place  before  the  miner  arrives. 
Then,  as  soon  as  he  comes  on  shift,  he  can  begin  setting 
up  and  drilling. 

STANDARD  TYPE  OF  TOOL  CAR 

The  tool  car  should  have  four  compartments — the  two 
larger  compartments  for  the  machine,  steel,  bar,  hose, 
blocks,  and  like  material,  the  two  smaller  ones  for 
wrenches,  oil  can,  gaskets,  side  rods,  and  smaller  ap- 
pliances generally.  This  car  should  be  designed  to  hold 
the  entire  equipment  in  a  small  space,  and  its  adop- 
tion will  obviate  the  necessity  of  using  several  trucks 
or  ore  cars.  At  the  end  of  the  shift,  the  equipment 
should  be  loaded  on  the  tool  car,  everything  being  put 
in  its  original  place,  and  moved  to  a  siding,  where  it 
should  be  attended  to  by  the  tool  "nipper"  on  the  next 
shift.  He  should  look  over  the  car,  refill  the  oil  can, 
replace  dull  with  sharp  steel,  and  see  that  everything 
is  in  first-class  order.  If  water  lines  are  not  provided 
in  the  drift,  water  cars  should  be  used.  Figs.  2  and 
3  are  drawings  of  practical  tool  and  water  cars  in  use 
in  several  mines  in  the  Southwest. 

STANDARD  EQUIPMENT  IN  RAISING  AND  STOPING 
A  standard  equipment  unit  for  raising  or  stoping 
should  consist  of  1  stoper  machine ;  52  pieces  of  selected 
stoper  steel;  one  50-ft.  air  hose  and  connections;  1  oil 


90 


STANDARDIZATION  OF  MINING  METHODS 


can,  filled  with  proper  machine  oil;  1  pick;  1  foot-block; 
1  monkey  wrench;  gaskets;  1  scraper;  1  powder 
sack;  1  fuse  sack;  1  tamping  stick.  If  the  stoper 
is  a  water  machine,  then  50  ft.  of  water  hose,  water 


1 


FIG.  3.    LEYNER  DRILL  WATER  CAR 

Correction:     Height  of  car  is  2  ft.  7  in., 
instead  of  7  ft.  7  in.,  as  shown. 

valve,  and  connection  should  be  included.  The  equip- 
ment should  be  loaded  on  the  tool  car  or  small  truck, 
and  handled  as  in  drifting. 

SHOVELING 

When  the  mucker  enters  the  drift  he  should  have  the 
following  equipment,  which  he  has  obtained  from  the 
tool  house  on  the  level:  1  short-handled  scoop  or  1 
square-pointed  shovel;  1  round-pointed  shovel;  1  pick; 
1  double  jack;  1  six-ft.  bar;  1  light  car,  obtained  at 


STANDARD  EQUIPMENT  91 

the  working  place.  Turnsheets  should  be  laid  in  all 
drifts  before  blasting,  so  that  the  mucker  will  be  more 
efficient  in  his  work.  Exhaustive  studies  have  been 
made  of  mucking  on  the  surface,  and  many  of  the  prin- 
ciples evolved  could  be  advantageously  applied  to  under- 
ground work.  Little  attention  has  usually  been  paid  to 
the  kind  of  shovel  which  is  given  to  the  mucker,  or 
whether  its  size,  shape,  design,  or  length  of  handle 
are  suitable  for  the  load  it  has  to  carry.  Too  much 
emphasis  cannot  be  laid  on  this  important  feature,  upon 
which  depends  the  efficiency  of  the  worker  and  the  cost 
of  the  operation. 

SHOVELS,  SHOVELING  MACHINES,  AND  SCRAPERS 

In  most  drifts  a  short-handled,  large  scoop  is  prefer- 
able, provided  turnsheets  have  been  first  laid  so  that  the 
mucker  can  shovel  from  a  smooth  bottom.  In  rare 
cases,  where  sulphides  are  to  be  handled,  a  smaller, 
square-point  shovel  should  be  used,  as  the  specific 
gravity  of  this  material  is  high.  If  no  turnsheets  have 
been  laid,  and  the  mucker  must  shovel  from  a  rough 
bottom,  then  a  small,  round-point  shovel  should  be  used. 
This  is  expensive  practice,  as  it  requires  far  greater 
exertion  to  shovel  from  a  rough  bottom  than  from  a 
smooth  surface,  experiments  showing  that  it  costs  ap- 
proximately 40%  more  than  if  turnsheets  are  laid  and 
a  short-handled,  square-pointed,  21-lb.  shovel  is  used. 

Shoveling  machines  are  used  in  large  stopes  and 
motor  drifts.  Though  a  large  amount  of  material  per 
shovel  can  be  handled  and  loaded  in  cars,  serious  de- 
lays are  frequent,  owing  to  breakdowns  which  require 
the  services  of  expert  mechanics  in  making  repairs. 
Scrapers,  when  operated  by  small  tugger  hoists,  are 
used  to  advantage  in  horizontal  top-slice  stopes  to  shovel 
and  transport  into  raises  the  ore  which  has  been  broken 
in  the  headings  driven  to  open  up  the  stopes.  After 
these  headings  are  opened,  a  large  number  of  stulls 
must  necessarily  be  put  up,  which  would  interfere  with 
the  action  of  the  scraper  and  prevent  its  use  in  the 


92  STANDARDIZATION  OF  MINING  METHODS 

slopes.  As  much  as  80  tons  has  frequently  been  han- 
dled with  one  of  these  scrapers  by  two  men  in  an  8-hour 
shift,  but  such  a  machine  can  be  used  to  advantage  only 
in  soft  ground.  In  stopes  where  there  is  hard  ground 
which  breaks  into  large  boulders  it  is  not  practicable 
unless  an  excessive  amount  of  explosive  is  used  to  break 
the  boulders,  and  this  adds  materially  to  the  cost.  The 
cars  used  should  be  light.  Considerable  effort  is  re- 
quired to  move  a  heavy  car,  and  if  one  man  must  handle 
it  alone  it  is  impossible  for  him  to  transport  much  ore. 

Frequent  sidings  and  switches  should  be  laid  in  long 
drifts  to  lessen  the  distance  for  hand  tramming.  Mule 
or  electric  haulage  should  be  used  from  these  sidings  to 
transport  ore  or  waste  to  its  destination. 

Where  short  trams  are  planned  for  the  mucker  to 
tram  either  ore  or  waste  into  raises  or  stopes,  the 
bosses  should  always  see  that  there  is  sufficient  room 
to  contain  all  the  material  which  will  be  trammed  there 
during  the  shift,  so  as  not  to  cause  a  delay  on  the 
part  of  the  mucker  in  waiting  for  chutes  to  be  drawn. 


Section  VII 

Prospecting 
and  Development 


ONE  of  the  most  important  branches  of  mining, 
and  one  which,  on  account  of  its  magnitude,  the 
variety  of  its  operations  and  amount  of  money 
involved,  offers  a  large  field  for  the  introduction  of 
standard  methods,  is  that  of  "prospecting  and  develop- 
ment   work."     "Prospecting"    and    "exploration"    are 
terms  applied  to  all  work  directed  toward  the  finding  of 
ore,  whereas  the  various  headings  driven  through  an 
orebody,   preparatory   to   mining,   are   usually   charac- 
terized as  "development  work." 

There  are  two  distinct  classes  of  mines:  those  whose 
ore  reserves  are  defined  by  churn  drilling  before  pro- 
duction begins,  and  those  which  prospect  and  develop 
their  reserves  in  the  usual  course  of  mining.  To  the 
first  belong  the  large  porphyries;  the  second  takes  in 
practically  all  the  higher-grade  mines.  These  so-called 
porphyries  have  the  advantage  of  having  their  ore 
blocked  out  for  many  years  ahead,  so  that  an  accurate 
estimate  of 'the  tonnage  can  be  made  and  the  size  of 
their  reserves  determined  in  advance,  whereas  the 
higher-grade  mines  have  a  much  smaller  ore  reserve.  In 
this  latter  division  are  mines  with  monthly  productions 


94  STANDARDIZATION  OF  MINING  METHODS 

ranging  from  2,000,000  to  7,000,000  Ib.  of  copper,  which 
have  been  steady  producers  for  many  years,  but  have 
rarely  had  more  than  a  few  years*  ore  in  sight  at  any 
one  time.  During  1916,  approximately  70%  of  all  the 
copper  produced  in  the  United  States  came  from  mines 
of  this  character,  the  remaining  30%  being  shipped 
from  properties  which  had  proved  orebodies,  previously 
explored  by  means  of  churn  drilling. 

One  of  the  principal  reasons  why  the  higher-grade 
mines  cannot  follow  the  methods  pursued  by  the  por- 
phyries, and  prospect  and  develop  large  ore  reserves 
at  the  outset,  is  that  the  nature  of  the  ground  is  such 
that  it  will  not  stay  open  for  any  length  of  time  with- 
out an  excessive  cost  for  repairs.  Therefore,  to  keep 
pace  with  the  continual  depletion,  and  to  maintain 
normal  ore  reserves,  it  is  essential  that  their  prospecting 
and  exploration  work  be  carried  on  simultaneously  with 
the  stoping. 

The  life  of  mines  is  a  subject  of  vital  importance 
to  everyone  connected  with  mining,  and  an  interesting 
question  arises  as  to  what  is  the  correct  amount  of 
prospecting  that  should  be  done.  If  the  work  is  carried 
on  too  extensively  it  entails  an  excessive  cost  for  repairs. 
On  the  other  hand,  if  these  operations  are  long  post- 
poned, the  life  of  the  mine  is  materially  shortened.  A 
precedent  established  by  a  number  of  companies  is  "to  do 
sufficient  prospecting  to  find  one  ton  of  ore  for  every 
ton  extracted."  To  follow  out  this  plan,  prospecting 
and  exploration  work  must  be  prosecuted  continuously. 
Intensive  prospecting  should  be  carried  on  in  the  neigh- 
borhood of  known  orebodies,  in  order  to  make  these 
ore-bearing  areas  as  productive  as  possible.  Favorable 
indications,  faults,  and  small  veins  leading  into  the 
country  rock  should  also  be  explored  by  means  of  inter- 
mediate drifts  at  the  time  of  discovery,  instead  of 
postponing  the  work  until  some  future  date,  when  the 
records  may  have  been  lost,  the  incidents  forgotten,  and 
the  cost  of  the  work  greatly  increased,  because  of  the 
necessity  of  reopening  old  workings. 


PROSPECTING  AND  DEVELOPMENT  95 

In  every  case  a  golden  mean  should  be  sought,  and 
a  fixed  ratio  established  between  the  amount  of  ore 
extracted  and  the  amount  of  prospecting  to  be  done. 
This  fixed  ratio  should  allow,  in  all  instances,  for  suf- 
ficient ore  to  be  developed  in  stopes  to  do  selective 
mining,  keep  up  the  normal  production,  and  maintain  the 
required  ore  reserve.  It  should  also  provide  for 
enough  openings,  carried  just  ahead  of  the  average 
workings,  to  benefit  the  ventilation  materially. 

The  exceptional  conditions  existing  since  1914,  attrib- 
utable in  the  first  instance  to  the  outbreak  of  the  war, 
secondly  to  labor  difficulties,  and  finally  to  a  decided 
shortage  of  labor,  have  caused  operators  to  postpone, 
in  a  large  measure,  necessary  prospecting  work  in  a 
praiseworthy  endeavor  to  maintain  maximum  produc- 
tion, and  as  a  consequence  the  ore  reserves  have  become 
seriousiy  depleted.  Prospecting  is  an  expensive  and 
hazardous  investment,  both  for  the  mine  owner  and  the 
prospector.  Though  an  occasional  heading  may  penetrate 
an  orebody,  exposing  enough  ore  to  yield  enormous  re- 
turns on  a  comparatively  small  investment,  thousands  of 
feet  of  prospecting  are  done  annually  with  practically 
negative  results.  One  of  the  problems  at  present  con- 
fronting the  mining  industry  is  how  to  make  up  for  the 
large  amount  of  prospecting  which  has  necessarily  had  to 
be  postponed  during  the  last  four  years,  so  that  normal 
ore  reserves  may  be  maintained  in  the  future.  To 
prosecute  this  work  at  a  minimum  cost  it  will  be  neces- 
sary to  standardize  all  operations  connected  with  it.  At 
present,  working  forces  are  constantly  being  changed, 
vacancies  generally  being  filled  by  men  who  require  a 
considerable  amount  of  training,  as  well  as  frequent 
supervision,  before  a  fair  day's  work  can  be  expected. 

The  employment  of  competent  instructors  to  train  the 
new  men  in  the  standard  methods  approved  by  the  oper- 
ating company  will  do  much  to  alleviate  the  conditions 
created  by  this  large  labor  turnover.  Men  who  are 
best  adapted  for  certain  classes  of  work  should  be 
selected,  complete  equipment  provided,  and  all  unneces- 


96  STANDARDIZATION  OF  MINING  METHODS 

sary  loss  of  time  eliminated.  This  will  make  possible  a 
larger  amount  of  prospecting  for  the  same  expenditure, 
lower-grade  material  will  then  become  of  commercial 
value,  and  thus  add  to  the  reserves  of  the  mine,  and, 
ultimately,  the  cost  per  pound  of  copper  will  be  lowered. 
The  previous  articles  in  this  series  describe  the 
standardized  methods  which  comprise  the  elements 
of  prospecting  and  development  work.  Examples  have 
been  given  of  what  may  be  gained  by  the  use  of  in- 
struction in  training  inexperienced  men  how  to  mine. 
The  following  illustrations  will  show  what  may  be  done 
by  taking  a  number  of  trained  and  skilled  miners  and 
giving  them  further  instructions  as  to  the  best  methods 
of  doing  certain  work,  thereby  increasing  their  value 
to  the  company. 

CONCRETING  A  FIVE-COMPARTMENT  MINE  SHAFT 

In  preparing  the  work  of  concreting  a  shaft  the 
plans  for  clearing  the  old  timbers,  for  moving  forms 
and  pouring  the  concrete  were  carefully  made  before- 
hand. The  crew,  working  under  the  direction  of  a  man 
thoroughly  familiar  with  standard  methods,  was  taught 
what  was  expected,  and  soon  reduced  the  work  to  regu- 
lar routine.  Twelve  men  were  employed,  including  the 
pipeman  and  foreman — two  men  to  a  compartment. 
They  held  the  places  originally  assigned  to  them 
throughout  the  entire  operations,  and  by  constant  ap- 
plication to  the  same  task  day  after  day  became  expert. 

The  estimated  time  for  pouring  five  feet  of  concrete 
was  ten  hours.  This  was  reduced  to  eight  in  a  short 
time,  and  finally  the  work  was  done  so  expeditiously  that 
it  became  a  question  of  how  to  utilize  the  remainder  of 
the  shift.  Before  long  it  became  possible  frequently  to 
concrete  two  sections  in  eight  hours,  and  on  one  occa- 
sion three  sections  were  put  in  within  that  time.  Accu- 
rate records  were  kept,  and  it  was  found  that  the  aver- 
age time  required  to  complete  the  work  of  putting  in  a 
5-ft.  section  of  concrete  was  6  hr.  14  min.,  which 
represented  a  reduction  in  the  total  working  time  (eight 


PROSPECTING  AND  DEVELOPMENT  97 

hours)  of  22.1%.    During  one  month  a  record  was  made 
of  4  hr.  31  min.,  or  50.6%  of  an  eight-hour  shift. 

These  remarkable  results  were  achieved  by  coopera- 
tion on  the  part  of  the  men,  and  because  they  were 
trained  in  the  beginning  to  plan  ahead  for  their  work 
and  take  all  necessary  tools  and  supplies  with  them  when 
going  on  shift.  Illustrations  of  this  kind  demonstrate 
the  practicability  of  introducing  standardized  methods 
in  other  classes  of  mining,  and  indicate  the  great  ad- 
vantages to  be  gained  thereby. 

COST  OF  PROSPECTING  AND  DEVELOPMENT  WORK 

Prospecting  and  development  work  consist  principally 
in  sinking,  drifting,  and  raising.  Sinking  is  the  most 
expensive  and  is  therefore  avoided  wherever  possible, 
deep  shafts  being  put  through  in  many  cases  by  means 
of  raises  instead  of  by  the  more  expensive  process  of 
sinking.  Drifts  are  driven  for  horizontal  prospecting, 
haulage,  ventilation,  and  similar  operations;  raises,  al- 
though used  for  like  purposes,  are  vertical  or  inclined. 

The  amount  of  drifting  and  raising,  or  "prospecting 
and  development  work,"  as  it  is  generally  called,  varies 
according  to  the  stage  of  development  the  property  has 
reached.  In  some  instances  as  much  as  30%  of  the  total 
cost  of  mining  is  expended  in  prospect  and  development 
work,  though  in  others  it  may  be  as  low  as  10%.  In 
prospects  which  have  not  reached  a  producing  stage, 
practically  the  whole  expenditure  goes  into  this  class  of 
work,  and  in  the  average  producing  mine  it  amounts  to 
about  25%  of  the  total  mining  cost.  In  extensive  veins, 
where  little  prospecting  is  required,  nearly  all  the  head- 
ings are  driven  in  ore,  but  in  the  majority  of  cases 
they  are  in  waste,  which  is  usually  harder  and  there- 
fore more  expensive  than  mining  in  ore. 

Some  of  the  most  important  items  in  the  cost  of  pros- 
pecting and  development  work  are  labor,  timber,  and  ex- 
plosives. Tables  I  and  II,  showing  the  amount  of 
footage  made  during  one  month,  give  the  proportionate 


98 


STANDARDIZATION  OF  MINING  METHODS 


expenditure  for  these  items  at  one  of  the  representative 
mines  in  Arizona. 


TABLE  I.    DETAILED  COSTS  OF  SEVEN   DRIFTS,  UNDER  VARYING 


CONDITIONS 


Example 

Labor 
$4.47 

oo 
Timber 
$0.31 

2 

5.84 

.50 

3 

4.89 

.33 

4 

4.43 

.28 

5 

5.80 

.75 

6 

5.43 

.54 

7 

4.14 

.11 

Cost  per  Foot- 


Ft. 


Average,         $5 . 00 


$0.40J8 


Powder 
$1.81 

1.45 

1.84 

2.50 

2.04 

1.96 

2.00 

$1.94 


Total 
$6.59 
7.79 
7.06 
7.21 
8.59 
7.93 
6.25 

$7.34 


.05 
.21 
.38 
.02 
.08 
.47 


1.22 


Of  the  total  expenditures,  the  labor  cost  was  68.12% 
of  the  total,  timber  amounted  to  5.45,  and  powder  to 
26.43  per  cent. 

TABLE  II.    DETAILED  COSTS  OF  SEVEN  RAISES  UNDER  VARYING 
CONDITIONS 


E  xample 
2 
4 
6 


Labor 
$5.23 
5.96 
5.10 
7.25 
8.24 
6.90 
4.18 

Timber             Powder 
$1.02                $1.66 
3.20                     .68 
1.88                   1.49 
2.46                   1.37 
1.96                   1.79 
2.07                   1.66 
1.55                     .98 

Total 
$7.91 
9.84 
8.47 
11.08 
11.99 
10.63 
6.71 

(a) 

1.12 

1.02 

1.16 

.82 

.72 

.80 

1.42 


Average,          Jb. 12  $2.02  $1.37  $9.51  0.99 

(a)  The  footage  per  man  shift  denotes  the  entire  work  which 
has  been  done  at  the  face,  such  as  drilling,  mucking,  laying 
track,  and  other  labor  of  the  sort. 

The  standard  custom  in  many  mining  districts  dic- 
tates that  the  drilling  of  one  round  per  shift  (regard- 
less of  the  amount  of  rock  broken  per  round)  shall  con- 
stitute a  day's  work,  even  though  it  were  possible  for 
the  miner  to  drill  and  blast  two  rounds  in  adjacent 
faces.  Demands  have  frequently  been  made  for  two 
men  on  a  machine,  which  if  acceded  to,  would  further 
increase  the  already  high  costs.  When  a  machine 
weighing  150  Ib.  or  more  is  used  it  is  often  con- 
sidered best  to  put  two  men  on  it,  but  this  would  ap- 
pear ridiculous  with  small  machines,  averaging  40  to 
50  Ib.  In  the  majority  of  cases  these  small  machines  do 
the  work  equally  well. 


PROSPECTING  AND  DEVELOPMENT  99 

NECESSITY  OF  INCREASING  FOOTAGE  To  LOWER  COSTS 

To  reduce  the  cost  of  prospecting  and  development 
it  is  necessary  to  increase  the  footage  per  man  shift, 
just  as  in  stoping  the  tonnage  per  man  shift  must  be 
increased  if  the  cost  per  ton  is  to  be  lowered.  In  other 
words,  this  means  the  drilling  of  deeper  rounds,  and  the 
blasting  and  shoveling  of  more  rock,  in  the  same  time 
and  with  practically  the  same  number  of  men  as  were 
needed  for  the  shorter  round.  To  accomplish  this  it  is 
absolutely  necessary  to  have  a  complete  equipment  on 
hand  for  the  driller,  a  regular  program  for  the  hand- 
ling of  the  work,  a  type  of  round  that  will  prove  most 
effective,  and  a  clean  place  to  set  up,  which  has  been 
previously  cleared  by  the  mucker.  In  addition  to  these 
essential  requisites,  many  other  factors  contribute  to 
standardization  underground,  such  as  transportation, 
explosives,  compressed  air,  and  ventilation.  These 
should  all  be  given  careful  attention. 

One  of  the  most  important  considerations  is  the  type 
of  round  to  be  drilled.  The  great  problem  is  to  "pull" 
as  much  ground  as  possible,  consistent  with  the  size 
and  shape  of  the  working  face.  The  blasting  of  deeper 
rounds  and  the  doing  of  more  efficient  work  do  not 
involve  greater  effort  on  the  part  of  the  miner  than 
his  usual  day's  work,  in  which  a  large  part  of  his  time 
is  spent  seeking  tools  and  supplies,  and  only  a  small 
part  in  drilling  and  blasting.  It  does  mean,  however, 
the  elimination  of  waste  effort  and  the  concentration 
of  his  energy  along  the  most  productive  lines. 

STAGES  IN  DRILLING  A  ROUND  OP  HOLES  AND 
SHOVELING 

In  general,  the  stages  in  drilling  a  round  of  holes, 
as  practiced  in  many  mines,  are  as  follows:  The  fore- 
man or  shift  boss  comes  into  the  face  of  a  drift,  raise 
or  winze,  and,  after  taking  in  the  situation  hastily,  usu- 
ally remarks  to  the  miner :  "Set  up  and  drill  a  round  of 
holes."  He  rarely  tells  him  where  to  find  the  complete 
equipment.  He  may  mention  the  place  where  a  machine 


100  STANDARDIZATION  OF  MINING  METHODS 

may  be  had,  but  never  gives  all  the  informaton  neces- 
sary to  drill  the  round.  Consequently,  the  miner  gets 
to  work,  and  after  finding  the  machine  and  column, 
brings  both  and  makes  the  "set-up."  Then  he  begins  to 
search  for  the  remainder  of  the  equipment  which  was 
used  by  the  preceding  shift.  He  finds  most  of  it  in  a 
reasonable  time,  but  some  things  are  generally  missing 
— a  few  necessary  wedges,  a  hose,  wrench,  wooden  block, 
or  some  other  minor  part  of  the  outfit. 

The  steel  must  next  be  obtained.  In  some  mines 
racks  are  placed  conveniently,  but  in  others  it  is  nec- 
essary to  go  a  long  distance  to  the  shaft  stations  to 
get  the  steel.  In  a  mine  where  a  number  of  different 
kinds  of  machines  are  used,  the  miner  often  makes  a 
mistake  and  brings  the  wrong  size,  which  necessitates 
his  returning  for  steel  which  will  fit  his  machine.  He 
then  connects  the  hose  and  water  lines  and  is  ready  to 
start  drilling  after  one-quarter  to  one-third  of  the  shift 
has  been  expended  in  preparations.  After  drilling  for 
a  few  minutes,  he  finds  it  necessary  to  get  oil  for  the 
machine.  As  no  special  oil  cans  are  available,  a  bottle 
or  ordinary  tin  can  is  used.  Often  the  miner  mixes 
car  oil  with  machine  oil  so  that  the  machine  will  not 
require  frequent  oiling.  He  next  pours  the  oil,  with 
the  grit  and  dirt  which  has  dropped  into  it,  into  the 
hose.  Apart  from  the  injury  arising  from  the  black  oil 
and  dirt  entering  the  machine,  the  oil  soon  attacks  the 
rubber  in  the  hose,  and  small  pieces  break  off  from 
time  to  time  and  clog  the  air  passages  at  the  valve. 
This  soon  results  in  machine  trouble. 

NORMAL  PROCEDURE  NEEDS  STANDARDIZATION 

The  type  of  round  is  of  next  importance.  In  approxi- 
mately 90%  of  the  rounds  drilled  in  metal  mines, 
the  cut  is  put  in  the  bottom  of  the  drift.  With  the 
exception  of  the  lower  corners,  this  is  the  most  difficult 
place  in  which  the  cut  can  possibly  be  put.  The  powder 
has  no  opportunity  to  break  a  deep  round,  on  account  of 
the  unfavorable  placing  of  the  cut, 


PROSPECTING  AND  DEVELOPMENT  101 

When  the  round  is  drilled  the  miner  fills  some  paper 
bags  with  gritty  material,  or  gets  some  clay  to  be  used 
as  stemming.  He  is  now  ready  to  go  for  his  powder 
and  load  the  holes.  By  this  time  the  shift  is  so  far 
gone  that  he  usually  finds  only  five  or  ten  minutes  left 
before  tally.  He  hurries  to  get  the  powder  into  the 
holes,  in  almost  any  fashion,  cramps  and  doubles  the 
fuse,  hastily  forces  in  some  stemming,  spits  the  fuse, 
calls  "Fire,"  and  leaves  the  face.  He  then  counts  the 
shots  and  chalks  up  the  number  of  missed  holes. 

The  entire  shift,  normally  for  the  purpose  of  placing 
and  loading  the  holes  in  such  a  manner  that  the  maxi- 
mum amount  of  ground  will  be  broken,  may  be  rendered 
ineffective  by  hasty  loading  and  firing;  and  this  most 
particular  stage  of  the  operations  is  nearly  always  the 
most  carelessly  attended  to  and  frequently  results  in 
missed  holes  and  a  short  round,  which  means  higher 
costs,  to  say  nothing  of  increased  danger  to  the  men. 

Drilling  is  usually  done  on  one  shift  and  shoveling 
on  the  next.  After  the  drift  has  progressed  far  enough, 
track  is  laid,  the  ditch  cut,  and,  if  necessary,  the  drift 
is  timbered.  As  a  preparatory  to  shoveling,  the  turn 
sheets  are  frequently  forgotten,  and  the  rock  is  blasted 
direct  on  the  ground.  This  makes  it  difficult  to  shovel 
from  the  rough  bottom,  causes  delays,  and,  as  a  conse- 
quence, generally  means  that  the  entire  round  is  not  all 
removed  by  the  end  of  the  shift,  leaving  some  near  the 
face.  When  the  machine  men  arrive,  they  will  be  de- 
layed, and  it  will  be  necessary  for  them  to  shovel  back 
from  the  face  on  account  of  their  not  having  a  clean 
set-up.  If  the  turn  sheets  have  been  forgotten,  the 
mucker  may  not  have  the  proper  kind  of  shovel,  and  so 
be  handicapped  in  his  work. 

THE  VALUE  OF  TIME  STUDIES 

The  following  time  studies  are  examples  from  a  num- 
ber made  to  obtain  an  accurate  record  of  the  distribu- 
tion of  the  miners'  time  and  to  ascertain  the  proportion 
of  the  shift  spent  in  actual  drilling. 


102  STANDARDIZATION  OF  MINING  METHODS 

TIME  STtrDY— DRILLING  "HOLES  5  FT.  DEEP  IN  HARD  PORPHYRY 

Per 

Distribution  of  Driller's  Time                            Minutes  Cent 

Walking  to  working  place 5  I.I 

Hunting  blocks  and  putting  up  bar 50  10.4 

Putting  up  clamp  and  machine II  2.3 

Building  staging 3  0.6 

Connecting  hose 9  1.9 

Adjusting  clamp  and  arm  of  machine 17  3.5 

Machine  out  of  order,  changing,  and  procuring  new  machine....    118  24.6 

Drilling 103$  21.6 

Changing  steel 36*  7.6 

7  1.5 

1  0.2 

2  0.4 
4  0.8 

30  6.3 


Oiling 

Picking  ground 

Cleaning  plugged  steel 

Talking 

Lunch 

Drawing  out  steel 2J  0.5 

Moving  machine  for  new  holes 56J  11.8 

Looking  for  tools 1  0.2 

Tearing  down  machine  and  column 3  0.6 

Cleaning  out  drift 2 

Blowing  out  holes 4  0.8 

Loading II  2.3 

Cutting  fuses  and  spitting 3  0.6 

Total 480  10000 

TIME  STUDIES  ON  DIFFERENT  GROUND 

~Per  ~Per  Per  Per 

Min.  Cent.  Min.    Cent.  Min.    Cent.  Min.  Cent. 

Drilling 102.8  21.4  88.3     18.4  99.3     20.7  64.5     13.4 

Loading 7.9  1.6  20.5       4.0  11.4       2.3  17.8       3.7 

Cutting  fuse  and  spitting.       6.4  1.3  2.5       0.5  4.2       0.9  8.1        1.7 
Setting  up,  oiling,  hunt- 
ing tools,  changing  po- 
sition, lunch,  etc. ....    362 . 9  75.7368.7     77.1  365.1     76.1  389.6     81.2 

Total 480.0   100.0  480.0  100.0  480.0  100.0  480.0  100.0 

Note — A  was  drilled  in  very  hard  ground,  consisting  mostly  of  silica  and 
pyrite;  B  in  medium  hard  ground,  principally  limestone;  C  in  oxidized  limestone, 
and  D  in  hard  silicified  limestone. 

After  averaging  the  figures  recorded,  it  was  found 
that  only  about  20%  of  the  miner's  time  was  spent  in 
actual  drilling,  3%  in  blasting,  and  the  remaining  77% 
in  searching  for  tools  and  supplies,  or,  in  other  words, 
"preparing  and  quitting." 

STANDARDIZATION  OF  OPERATIONS 

The  studies  show  that  by  far  the  larger  part  of  the 
miner's  time  is  not  spent  in  productive  labor,  even 
though  his  efforts  are  equivalent  to  the  energy  ex- 
pended in  a  good  day's  work.  The  aim  of  standard- 
ization of  drilling  operations  is  to  eliminate  waste  ef- 
forts so  far  as  possible,  and  to  make  a  large  proportion 


PROSPECTING  AND  DEVELOPMENT  103 

of  this  77%  of  the  miner's  time  as  productive  as  that 
spent  in  actual  drilling. 

When  a  drift  is  to  be  driven,  the  shift  boss  should 
look  over  and  carefully  examine  the  face  during  the 
preceding  day.  He  should  then  instruct  his  tool  "nip- 
per" to  assemble  the  entire  equipment  on  the  car  de- 
signed for  that  purpose  and  take  it  to  the  working 
place  before  the  miner  comes  on  shift.  He  should  also 
see  that  turn  sheets  are  laid  at  the  face.  Then,  when 
the  miner  arrives  he  finds  everything  ready.  All  that 
is  necessary  is  to  set  up  his  machine,  make  air  and 
water  connections,  and  begin  drilling. 

By  this  time  the  shift  boss  makes  his  visit  and  in- 
quires regarding  the  number  of  holes  and  type  of  round 
to  be  drilled.  If  the  miner  has  previously  received  in- 
struction in  drilling  other  drifts  in  this  particular  mine, 
he  will  be  able  to  satisfy  the  boss  as  to  the  kind  of 
round  he  is  preparing  to  drill ;  but  if  he  is  not  familiar 
with  the  type  which  has  become  standard,  the  shift 
boss  sends  the  drill  instructor  to  him,  who  helps  him  in 
drilling  a  standard  round.  This  should  be  the  same 
under  all  circumstances,  with  the  exception  that  in  soft 
ground  some  of  the  holes  around  the  edges  of  the  drift 
are  omitted,  whereas  in  hard  ground  the  number  is 
increased.  If  a  ditch  is  necessary,  one  of  the  lifters 
should  be  kept  down.  Great  care  should  be  exercised  in 
having  the  drift  kept  on  lines,  and  a  uniform  grade 
should  be  maintained  wherever  possible.  It  is  also  im- 
portant that  the  air  pressure  be  kept  up,  in  order  that 
the  machines  may  do  effective  work. 

If,  in  the  course  of  drilling,  the  machine  should  get 
out  of  order,  or  the  supply  of  steel  run  low,  the  miner 
may  obtain  a  new  machine  and  a  fresh  supply  of  steel 
from  the  tool  house  on  the  same  level,  where  a  surplus 
should  always  be  on  hand,  so  that  he  may  not  be  de- 
layed longer  than  is  absolutely  necessary.  The  old 
machine  should  be  taken  back  to  the  tool  house  and 
checked  in  before  the  new  machine  is  taken  out.  This 
provides  for  a  perpetual  inventory  of  all  such  equip- 


104  STANDARDIZATION  OF  MINING  METHODS 

ment.  The  man  in  charge  of  the  tool  house,  who  is  also 
the  powder  man,  sends  the  machine  to  the  repair  shop, 
either  on  surface  or  underground,  as  the  case  may  be. 

All  machines  require  oiling  from  time  to  time  during 
the  shift,  and  a  can  filled  with  proper  machine  oil 
should  be  included  in  the  equipment  on  the  tool  car. 
The  injurious  effects  of  constant  oiling  through  the  air 
hose  should  be  explained  to  the  miner,  and  he  should  be 
instructed  to  pour  the  oil  into  the  receptacles  designed 
for  that  purpose. 

Having  drilled  the  round,  the  miner  disconnects  the 
air  and  water  lines,  tears  down  the  machine,  loads  the 
outfit  on  the  tool  car  and  pushes  it  back  into  a  siding, 
where  it  should  remain  if  he  is  to  drill  in  the  same 
face  the  next  day.  On  the  following  shift,  the  con- 
tents of  the  car  should  be  checked  over  by  the  tool 
"nipper,"  who  exchanges  dull  steel  for  sharp,  refills  the 
oil  can,  looks  over  the  equipment  and  sees  that  every- 
thing is  complete.  The  ventilating  pipe  near  the  face 
should  next  be  removed,  and  the  miner  should  see  that 
sufficient  turn  sheets  have  been  properly  laid. 

THE  USE  OP  EXPLOSIVES 

The  miner  then  clears  the  holes  with  his  blow  pipe, 
takes  his  powder  and  fuse  sacks,  and  goes  to  the  powder 
magazine,  where  he  is  supplied  with  the  number  of 
sticks  of  powder  and  capped  fuses  for  which  the  order 
he  has  previously  obtained  from  the  shift  boss  calls. 
The  powder  man  also  gives  him  a  supply  of  stemming  to 
be  used  in  tamping  the  holes.  He  places  all  these  things 
in  the  sacks  provided  for  the  purpose,  and  then  re- 
turns to  the  face  and  starts  loading,  being  careful  to  use 
a  wooden  tamping  stick,  and  to  slit  the  paper  covers  on 
the  sticks  of  powder  (except  in  the  case  of  wet  holes), 
so  that  in  forcing  it  in  he  will  eliminate  all  air  spaces. 
Having  placed  the  powder  and  primer  in  the  holes,  he 
fills  the  remainder  of  the  space  with  stemming  to  within 
about  6  in.  of  the  collar,  and  thoroughly  tamps  it,  tak- 
ing care,  however,  not  to  damage  the  fuse.  When  ready 


PROSPECTING  AND  DEVELOPMENT  105 

to  spit  the  fuse,  he  calls  another  miner  to  his  assist- 
ance and  lights  the  fuses,  igniting  them  in  the  order  in 
which  they  should  be  fired,  which  is  usually  the  cuts 
first,  then  the  side  holes,  back  holes,  and,  finally,  the 
lifters.  Having  done  this,  he  leaves  the  face  and  waits 
at  a  safe  distance  to  count  the  shots,  seeing  that  no  one 
enters  the  working  place.  The  number  of  missed  holes 
is  then  chalked  on  the  blackboards  placed  for  that  pur- 
pose for  the  information  of  the  next  shift. 

It  usually  takes  the  miner  the  entire  shift  to  drill, 
load,  and  fire  a  6-  or  7-ft.  round  in  a  drift  5i  ft. 
wide  by  8  ft.  high,  in  average  ground.  With  the  use 
of  the  standard  round,  described  in  a  previous  article, 
this  depth  of  ground  has  been  blasted  consistently  for 
periods  of  15  consecutive  days.  In  smaller  drifts,  such 
as  4  x  6  ft.,  it  is  not  practicable  to  use  as  deep  rounds 
as  in  the  large  drifts,  and  consequently  it  will  not 
take  the  miner  a  full  shift  to  drill  a  small  round  under 
average  conditions.  Consequently,  wherever  possible, 
two  working  faces,  near  each  other,  should  be  chosen. 
The  miner  in  this  case,  having  drilled  a  round  in  one 
face,  can  tear  down  and  set  up  in  another;  and  it  would 
be  entirely  possible  for  him  to  drill,  if  not  two  whole 
rounds,  at  least  a  round  and  a  half.  In  this  event  he 
would,  of  course,  leave  the  loading  and  firing  of  the 
first  round  until  near  the  end  of  the  shift. 

CLEARING  THE  FACE  AND  TIMBERING 

The  mucker,  when  coming  on  shift,  should  get  his 
complete  equipment  from  the  tool  house  on  the  level 
where  he  is  to  work.  After  completing  his  shift,  if  he 
is  to  continue  working  in  this  particular  place,  this 
equipment  should  be  left  in  the  drift  until  he  comes  on 
shift  again.  When  the  tool  "nipper"  makes  his  rounds, 
he  should  look  over  the  mucker's  outfit  at  the  time  he 
inspects  the  miner's  tool  car,  and  replace  the  dull  picks 
with  sharp  ones  and  make  other  necessary  adjustments. 
It  is  the  mucker's  duty  before  going  off  shift  to  see 
that  the  turn  sheets  are  laid  near  the  face.  His  work 


106  STANDARDIZATION  OF  MINING  METHODS 

should  be  planned  beforehand  by  the  shift  boss,  who  ar- 
ranges for  cars,  the  transportation  and  destination  of 
the  waste,  and  does  everything  possible  to  facilitate  the 
work,  so  that  when  the  driller  comes  on  shift  the  next 
morning  he  has  a  clean  place  in  which  to  set  up  and 
drill. 

Mine  cars  should  be  light  and  easily  handled,  and  the 
track  carried  as  near  the  face  as  possible  in  order  to 
avoid  unnecessary  shoveling.  Tracks,  ties  and  rails 
should  be  standardized  as  far  as  practicable. 

If  the  drift  requires  timbering,  it  should  not  be 
arched;  but,  generally,  three  back  holes  are  needed  to 
square  it  up  so  that  timbers  can  be  put  in  without  extra 
plugging.  The  timber  man  as  a  rule  is  not  put  in  the 
drift  until  the  face  has  progressed  30  or  40  ft.,  but 
sometimes  it  is  necessary  that  the  timber  be  kept  up 
close  to  the  face.  In  general,  the  timber  man  should 
get  his  timbers  at  the  timber  station  on  the  level  and 
take  them  to  the  drift  in  question.  He  usually  has  a 
helper  to  assist  him  in  setting  them  up;  and,  as  they 
are  all  of  standard  size  for  this  character  of  drift,  they 
require  no  cutting  underground. 

DETAILS  OF  RAISE  DRILLING 

The  operations  connected  with  the  drilling  of  raises 
may  be  standardized  along  lines  similar  to  those  de- 
scribed in  driving  drifts.  The  miner  should  find  his 
equipment  waiting  for  him;  and,  soon  after  taking  the 
machine  and  necessary  parts  up  the  raise,  should  be 
ready  to  begin  work.  The  shift  boss  should  outline  the 
work  and  see  that  the  driller  is  prepared  to  put  in  the 
standard  round  for  raises.  If  necessary,  the  drill  in- 
structor should  be  sent  to  his  assistance.  When  rounds 
have  been  drilled,  loaded,  and  fired,  and  the  rock  has 
been  drawn  down  the  raise  far  enough  to  be  out  of  the 
way,  the  back  of  the  raise  being  about  12  ft.  above  the 
floor,  it  is  necessary  to  put  in  a  set  of  timbers.  In 
timbering,  the  principle  of  putting  in  standard  sets 
should  be  followed,  carrying  up  a  standard  raise  with 


PROSPECTING  AND  DEVELOPMENT  107 

chute,  manway,  and  timber  compartment  as  far  as 
practicable. 

These  standardized  operations  apply  equally  well  to 
stop  ing,  inasmuch  as  stoping  operations  are  usually,  in 
the  broad  sense  of  the  word,  a  combination  of  both 
drifting  and  raising,  followed  by  timbering,  with  or 
without  waste  filling. 

Provision  should  be  made  for  good  ventilation  in  all 
drifts,  raises  and  stopes;  and,  where  necessary,  blowers 
with  ventilating  pipe  should  be  installed  to  keep  a  supply 
of  fresh  air  at  the  working  face. 

The  night-shift  bosses  should  come  early  enough  to 
consult  with  those  on  the  day  shift,  so  that  they  may 
plan  the  work  intelligently  before  the  men  arrive;  and 
when  going  oif  shift  should  leave  a  complete  record  of 
what  has  been  done  during  the  night,  in  order  that  the 
day  bosses,  when  they  come  on  shift,  may  continue  the 
work  without  delay. 

THE  IMPORTANCE  OF  COSPERATIVE  EFFORT 

A  continuous  repetition  of  the  above  operations  forms 
the  basis  of  prospect  and  development  work;  but,  that 
it  may  proceed  smoothly  and  without  serious  interrup- 
tion, many  other  matters  should  receive  consideration. 
The  personal  equation  is  one  which  should  not  be  over- 
looked. The  attitude  of  the  shift  bosses  and  foremen 
should  be  such  that  they  can  maintain  discipline,  but 
at  the  same  time  have  the  full  cooperation  of  the  men. 
It  is  impossible  to  produce  the  best  results  unless  har- 
monious relations  exist. 

The  shift  boss  should  make  a  study  of  each  man  to 
learn  the  particular  class  of  work  for  which  he  is  best 
adapted.  One  man  may  be  especially  fitted  for  raising; 
another  may  do  better  at  drifting,  timbering,  or  some 
other  detail  in  mining.  It  is  sometimes  necessary  to 
change  a  new  man  around  until  he  has  been  finally  placed 
in  the  right  job ;  but  frequently  mistakes  are  committed 
by  bosses  who  make  a  practice  of  changing  men  around 
constantly,  thereby  preventing  their  making  the  show- 


108  STANDARDIZATION  OF  MINING  METHODS 

ing  possible  were  they  permitted  to  become  thoroughly 
familiar  with  one  particular  working  place. 

THE  LABOR  TURNOVER  PROBLEM 
One  of  the  economic  wastes  in  mining  is  in  hiring 
and  discharging  men — a  problem  which  has  not,  as  yet, 
been  satisfactorily  solved.  An  endeavor  is  being  made 
at  several  camps  to  eliminate  this  expense  by  having  a 
central  employment  office.  In  case  a  man  does  not 
make  good  in  the  division  in  which  he  is  first  placed, 
he  is  sent  back  to  the  employment  office,  where  he  ob- 
tains a  transfer  and  is  tried  out  under  another  foreman. 
This  practice  is  continued  until  he  either  finds  the  work 
for  which  he  is  suited  or  is  discharged  as  incompetent 
to  hold  a  job.  In  the  majority  of  camps,  however, 
though  the  hiring  is  done  by  the  central  employment 
office,  the  discharging  is  left  entirely  to  the  individual 
judgment  of  the  bosses.  With  this  system  the  bosses 
should,  and  in  many  cases  do,  receive  specific  instruc- 
tions to  discharge  a  man  only  for  absolute  inefficiency 
or  for  conduct  contrary  to  company  rules. 

Experiments  in  various  forms  have  been  tried  out 
in  order  to  provide  an  incentive  for  additional  footage 
over  and  above  that  made  on  day's  pay  by  the  average 
miner.  One  plan  was  the  contract  system,  whereby  a 
man  was  paid  so  much  per  foot,  regardless  of  the  total 
footage.  Another  was  the  bonus,  which  guaranteed  a 
day's  pay  to  every  man,  and  at  the  same  time  com- 
pensated him  for  any  additional  footage  made  over  and 
above  the  average. 

TIME  STUDIES  LEAD  TO  MUTUALLY  ADVANTAGEOUS 
RESULTS 

To  arrive  at  something  which  might  be  considered 
a  basis  for  an  equitable  bonus  system,  time  studies  were 
made  in  drilling  the  standard  round,  to  determine 
what  would  constitute  a  fair  day's  work.  By  this 
is  meant  not  the  maximum  amount  of  work  produced 
by  the  exceptional  driller,  but  that  which  can  be  pro- 
duced by  the  average  man  using  standard  methods. 


PROSPECTING  AND  DEVELOPMENT  109 

The  purpose  of  time  studies  is  to  furnish  the  neces- 
sary information  upon  which  a  day's  work  may  be 
planned  and  an  efficient  system  built  up,  and  it  is  not 
intended  to  speed  up  the  men  or  to  induce  them  to  work 
any  harder.  As  may  be  seen  from  the  few  time  studies 
given  in  this  paper,  the  miner  who  puts  in  a  round  of 
holes  by  drilling  20%  of  the  time,  and  spends  the  re- 
mainder in  obtaining  tools  and  supplies,  would  not 
work  any  harder  if  he  should  put  in  40%  of  the  time 
drilling,  complete  two  rounds,  and  have  all  equipment 
and  accessories  brought  to  him. 

In  the  minds  of  the  men,  unfortunately,  the  idea  of 
time  studies  is  so  closely  associated  with  "speeding  up 
the  work"  that  they  are  inclined  to  look  upon  them  with 
suspicion,  and  much  good  which  might  be  attained  is 
therefore  lost.  This  prejudice  on  the  part  of  the  miners 
to  stop-watches  and  time  studies  has  some  foundation, 
because  many  of  those  who  have  made  time  studies  have 
been  novices  at  the  work  themselves,  and  the  bosses, 
not  understandng  the  principle  underlying  these  studies, 
proceeded  to  order  the  men  around  and  speed  them  up. 
This  has  greatly  retarded  the  work  which  might  have 
been  accomplished  by  these  methods. 

One  of  the  principles  adopted  by  the  National  Indus- 
trial Conference  Board  for  the  period  of  the  war  was 
that  "maximum  production  should  be  maintained,  and 
anything  which  interferes  with  it  or  tends  artificially 
to  increase  the  cost  of  production  is  discouraged." 

This  is  well  stated.  Only  by  the  use  of  time  studies 
and  cost  sheets  is  it  possible  to  arrive  at  the  various 
weaknesses  in  underground  mining  systems.  Until  these 
weaknesses  have  been  discovered  and  eliminated,  it  is 
impossible  to  operate  with  the  highest  degree  of  effi- 
ciency, which  means  maximum  production;  and  until 
definite  figures  for  a  fair  day's  work  have  been  ascer- 
tained, no  satisfactory  bonus  system  can  be  evolved. 

After  the  deficiencies  in  the  different  underground 
systems  have  been  fully  brought  to  light,  and  a  definite 
program  has  been  outlined  for  the  miner,  it  will  be  far 


110  STANDARDIZATION  OF  MINING  METHODS 

better  for  him  personally,  as  well  as  for  the  company, 
to  make  a  good  showing;  for  in  this  way  the  cost  of 
mining  will  be  lowered,  more  low-grade  ore  will  be 
made  commercial,  and  the  life  of  the  mines  thereby  in- 
creased. The  company  will  be  in  a  position  to  pay  a 
substantial  bonus  to  the  man  who  has  gone  through  a 
course  to  make  his  average  day's  work  an  achievement 
in  which  every  move  has  been  made  to  count. 


INDEX 


Character  of  earlier  types  of 
raises,  3 

Development  of  standard 
raise,  3 

Expansion  of  operations 
makes  standardization  in- 
creasingly important,  1 

Influence  of  safety-first  move- 
ment, 4 

Need  for  uniformity  impera- 
tive, 2 

Standard  chute  door,  17 

Standard  gratings  for  timber 
compartments,  16 

II 

Cost  of  breaking  ground,  19 
Development      of      standard 

round,  21 
Earlier  types  of  piston  drills, 

20 

Experimental  types,  22 
Results,  29 
Standard  round  for  drifts,  24 
Standard  round  for  raises,  26 
Standard  round  for  top-slice 

stopes,  26 
Standard    round    in    tunnel 

work,  21 

III 

All  workings  must  be  venti- 
lated, 37 

Careful  study  of  ventilation 
needs  necessary,  33 


Cost  sheets  prove  value  of 
good  air,  40 

Humidity  causes  many  mines 
to  seem  hot,  32 

Jets  and  blowers,  39 

Separate  system  for  develop- 
ment work,  35 

Simplest  system  uses  one  cen- 
tral installation,  36 

Standardized  doors,  45 

Ventilating  systems  may  aid 
fire  fighting,  34 

Ventilation  may  be  standard- 
ized, 39 

IV 

Capping  of  fuses,  52 
Classes  of  stemming  used,  56 
Danger  from  missed  holes,  60 
Formulating  of  blasting  rules 

difficult,  63 

Gases  from  explosives,  61 
Loading   and   blasting   prac- 
tice, 59 

Mechanical  fuse  cutter,  51 
Stemming  increases  efficiency, 

55 

Stemming  or  tamping,  53 
Use  of  American  auger  ma- 
chine, 58 

Value  of  clay  for  stemming, 
57 


Causes  of  mine  fires,  65 
Each  man's  duty  in  case  of 
fire,  67 


Equipment,  77 

Fire  fighting  in  workings,  76 
Gob  fires,  79 
Helmet  work,  69 
Mechanical  ventilation,  78 
Methods  used  somewhat  ques- 
tionable, 68 
Natural  ventilation,  79 
Posting  of  fire  rules,  75 
Purpose  of  fire  doors,  71 
Standard  method  for  protect- 
ing shaft  and  stations,  70 

VI 

Care  of  rock-drilling  ma- 
chines, 83 

Distribution  of  tools  and  sup- 
plies, 82 

Handling  steel  underground, 
86 

Necessity  for  steel  racks,  86 

Repairs  to  rock  drills,  83 

Shoveling,  90 

Shovels,  shoveling  machines 
and  scrapers,  91 

Small  machines,  85 

Sound  of  machine  no  indica- 
tion of  work  done,  84 


Standard  equipment  for  drift- 
ing work,  88 

Standard  equipment  in  rais- 
ing and  stoping,  89 

Standard  type  of  tool  car,  89 

VII 

Concreting  mine  shaft,  96 

Clearing  the  face  and  tim- 
bering, 105 

Cost  of  prospecting  and  de- 
velopment work,  97 

Details  of  raise  drilling,  106 

Importance  of  co-operative 
effort,  107 

Labor  turnover  problem,  108 

Necessity  of  increasing  foot- 
age to  lower  costs,  99 

Normal  procedure  standard- 
ized, 100 

Stages  in  drilling  and  shovel- 
ing, 99 

Standardization  of  opera- 
tions, 102 

Time  studies  result  advan- 
tageously, 108 

The  value  of  time  studies,  101 

Use  of  explosives,  104 


/o 


v  - 


. 


s 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


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WILL.  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  5O  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


SEP     6    J&32 
7    1S32 

SEP  28    1932 


OCT    3    1932 


APR    19   1933 

*>  **  1983 

OCT31  1933 
NOV  23  1933 


£61   8    d3S 


C?   8   193V 


SEP  IB  1938 

,APR  271983 
BEC.ciR.wr  5-83 


LD  21-20m-6,'32 


VB  1551 


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